Science Grade 06 Unit 04 Exemplar Lesson 01: Elements, Compounds, and Evidence of Change

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1 Grade 06 Unit 04 Exemplar Lesson 01: Elements, Compounds, and Evidence of Change This lesson is one approach to teaching the State Standards associated with this unit. Districts are encouraged to customize this lesson by supplementing with district-approved resources, materials, and activities to best meet the needs of learners. The duration for this lesson is only a recommendation, and districts may modify the time frame to meet students needs. To better understand how your district may be implementing CSCOPE lessons, please contact your child s teacher. (For your convenience, please find linked the TEA Commissioner s List of State Board of Education Approved Instructional Resources and Midcycle State Adopted Instructional Materials.) Lesson Synopsis In this unit, students will differentiate common compounds by name and symbol. Students should see examples of reactions between substances that produce new substances very different from the reactants. They will recognize that the formation of a new substance may be identified using the evidence of a possible chemical change, such as production of a gas, change in temperature, production of a precipitate, or change in color. In the previous lesson, students learned about elements. Students will be expected to recognize a few common compounds and their chemical formulas. This is new material for. In the previous set of TEKS, this material was covered in Grade 7. Formulas and equations are studied in-depth in the Grade 8. TEKS The Texas Essential Knowledge and Skills (TEKS) listed below are the standards adopted by the State Board of Education, which are required by Texas law. Any standard that has a strike-through (e.g. sample phrase) indicates that portion of the standard is taught in a previous or subsequent unit. The TEKS are available on the Texas Education Agency website at Scientific Process TEKS 6.5 Matter and energy. The student knows the differences between elements and compounds. The student is expected to: 6.5C Differentiate between elements and compounds on the most basic level. Supporting Standard 6.5D Identify the formation of a new substance by using the evidence of a possible chemical change such as production of a gas, change in temperature, production of a precipitate, or color change. 6.1 Scientific investigation and reasoning. The student, for at least 40% of instructional time, conducts laboratory and field investigations following safety procedures and environmentally appropriate and ethical practices. The student is expected to: 6.1A Demonstrate safe practices during laboratory and field investigations as outlined in the Texas Safety Standards. 6.1B Practice appropriate use and conservation of resources, including disposal, reuse, or recycling of materials. 6.2 Scientific investigation and reasoning. The student uses scientific inquiry methods during laboratory and field investigations. The student is expected to: 6.2A Plan and implement comparative and descriptive investigations by making observations, asking well-defined questions, and using appropriate equipment and technology. 6.2C Collect and record data using the International System of Units (SI) and qualitative means such as labeled drawings, writing, and graphic organizers. 6.2D Construct tables and graphs, using repeated trials and means, to organize data and identify patterns. 6.2E Analyze data to formulate reasonable explanations, communicate valid conclusions supported by the data, and predict trends. 6.4 Scientific investigation and reasoning. The student knows how to use a variety of tools and safety equipment to conduct science inquiry. The student is expected to: 6.4A Use appropriate tools to collect, record, and analyze information, including journals/notebooks, beakers, Petri dishes, meter sticks, graduated cylinders, hot plates, test tubes, triple beam balances, microscopes, thermometers, calculators, computers, timing devices, and other equipment as needed to teach the curriculum. GETTING READY FOR INSTRUCTION Performance Indicators page 1 of 23

2 Grade 06 Unit 04 PI 01 Create a tabbed or layered book. On each tab, include the formula of a compound, elements, and number of atoms present in each compound. On the back of the book, write a summary that explains the evidence for a chemical change taking place as a new substance is formed. Standard(s): 6.2E, 6.5C, 6.5D ELPS ELPS.c.5B, ELPS.c.5F, ELPS.c.5G Key Understandings A compound is a substance made by chemically combining two or more elements. Do compounds have different properties than the substances from which they are made? The formation of a new substance may be identified by the evidence of a chemical change: production of a gas, change in temperature, production of a precipitate, or color change. What are some common signs that a chemical change has taken place? Vocabulary of Instruction compound chemical formula subscript molecule precipitate Materials apron (1 per student, per Station D) baking powder (15 ml per group, per Station E) baking soda balloons beakers calcium chloride chalk (1 piece per group) cup (foam, 1 per Station B) cups (clear plastic, 2 per Station C) food coloring (red, 1 bottle, per Station D) funnel (plastic or paper, 1 per Station E) glue or tape (1 per student) graduated cylinder honey (small amount per group) hydrogen peroxide (per group) index cards (large, 1 per student) jars (baby food size, 2 per Station D) liquid bleach (a few drops, per group per Station D) markers or colored pencils (per group) MSDS (hydrogen peroxide, 1 per class) paper (see Advance Preparation, 5 half sheets per student) paper towels (several per group) Periodic Table of the Elements (see Advance Preparation, 1 per student) pipettes (to dispense wet ingredients into test tubes, 2 per group) plastic interlocking blocks (3 different colors, 12 per pair) plastic water bottle (1,500 ml, empty, 1 per Station E) raw potato slice (thin sliced, cut in half, see Advance Preparation, 2 halves per group) resealable plastic bag (freezer weight, pint sized, 1 per group at Station A) safety goggles (1 per student) sand (small handful per group) scissors (1 per student) scoopulas (to dispense dry ingredients into test tubes, 2 per teacher) spoons (plastic) staples, tape, or glue (per group) table salt (small amount per group) test tube rack (1 per group) test tubes (5 per group) thermometer (with backing) timer triple beam balance vinegar water page 2 of 23

3 Attachments All attachments associated with this lesson are referenced in the body of the lesson. Due to considerations for grading or student assessment, attachments that are connected with Performance Indicators or serve as answer keys are available in the district site and are not accessible on the public website. Handout: Building Blocks of Matter II (1 per pair) Handout: Compounds and Elements (1 per student) Teacher Resource: Compounds and Elements KEY Teacher Resource: Compounds and Elements Matching Cards (see Advance Preparation, 1 set per student, Handout: Water or Not (1 per group) Handout: Elements, Compounds, and Evidence of Change (1 per student) Teacher Resource: Elements, Compounds, and Evidence of Change KEY Teacher Resource: Creating a Tabbed Book Resources None Identified Advance Preparation 1. Prior to Day 1, consult the MSDS for all the chemicals used in the lesson for safety precautions and safe disposal. See the Resources and References section for a website with MSDS. 2. Prior to Day 1, prepare the Engagement activity. Pour a small amount of hydrogen peroxide in one beaker. Label this beaker Y. Pour an equal amount of water in another beaker. Label this beaker X. Repeat this process for each group. 3. If you have not already had students attach a copy of the Periodic Table from the Grade 8 STAAR Reference Materials in their science notebooks, download and print copies of the Periodic Table from the site listed in Resources and References (1 per student). This is the chart that students will use on the Grade 8 STAAR test. Students should be using this chart so they are familiar with it. 4. Print set of cards from the Teacher Resource: Compounds and Elements Matching Cards. There are four sets of cards on the page. Each student will need one set of cards, so cut apart the sets for easy distribution. 5. Prior to Day 5, prepare beakers of water and Hydrogen peroxide for student designed investigations. Prior to Day 6, thinly slice a raw potato so that a slice will fit in the beakers used to hold the water and hydrogen peroxide. Cut each slice in half. Each group will receive two halves of a potato slice. Note: The day the potatoes will be needed may vary, so store potato slices in water to prevent oxidation. 6. Prior to Day 8, copy and laminate the Teacher Resource: Evidence of Chemical Reactions Station Cards. 7. Prior to Day 8, prepare station materials per the Teacher Resource: Evidence of Chemical Reactions. 8. Prior to Day 12, determine requirements and materials for the Performance Indicator. 9. Prepare attachment(s) as necessary. Background Information In, students will concentrate on developing an understanding of elements and compounds. It is important that students learn the differences between elements and compounds based on observations, description of physical properties, and chemical reactions. Elements are represented by chemical symbols, while compounds are represented by chemical formulas. In previous units, students were introduced to elements; compared the physical properties of metals, nonmetals, and metalloids, and the elements general placement on the periodic table according to physical properties. In this unit, students differentiate between common elements and compounds by name and symbol. Students first learn what a compound is and how it is represented in a chemical formula. Students will then investigate examples of reactions between substances that produce new substances. They will learn to recognize that the formation of a new substance may be identified using the evidence of a possible chemical change, such as production of a gas, change in temperature, production of a precipitate, or change in color. After this unit, these concepts are not directly taught again in. STAAR Notes: This is an important foundational piece for the understanding of elements, compounds, and their properties. In Grade 7, students will study physical and chemical changes as they relate to the digestive system. In Grade 8, students will study chemical formulas and equations, as well as chemical reactions as evidence of the formation of new substances with different properties. 6.5C is identified as a Supporting Standard that will be tested on STAAR Grade 8 under Reporting Category 1: Matter and Energy. Although 6.5D is not identified as a Supporting Standard, identifying the formation of a new substance by using evidence of chemical change builds content for Supporting Standard 7.6B and Readiness Standard 8.5E. Both Supporting Standard 7.6B and Readiness Standard 8.5E will be tested on STAAR Grade 8 under Reporting Category 1: Matter and Energy. INSTRUCTIONAL PROCEDURES page 3 of 23

4 Instructional Procedures ENGAGE What a Difference an Atom Makes 1. Divide students into groups and review safety procedures for handling unknown liquids. 2. Distribute a set of marked beakers to each group. 3. Instruct students to make some observations about the beakers in their science notebooks. After students have written some observations ask each group to share one observation. 4. Say: Even though the two substances look the same, they have very different properties. The substance in beaker X is drinkable. The substance in beaker Y is not drinkable, and in its pure form could be fatal if ingested. Both substances may be used to clean wounds but one is more effective than the other. Notes for Teacher NOTE: 1 Day = 50 minutes Suggested Day 1 Materials: safety goggles (1 per student) beakers (small, labeled, see Advance Preparation, 2 per group) Water (per group) hydrogen peroxide (per group) MSDS (hydrogen peroxide, 1 per class) Safety Notes: Instruct students not to taste contents of either beaker. Remind them to be careful not to get any liquid on themselves. 5. Write the chemical formula for both beaker X (H 2 O) and for beaker Y (H 2 O 2 ) on the board. Under the formula draw the structure of the substances. Do NOT write the names of the liquids yet. Review the MSDS for hydrogen peroxide safety and disposal. 6. Ask: Water molecule Hydrogen peroxide molecule Instructional Note: One of the sets of beakers will be used in a later teacher demonstration. What do the circles represent? (Different elements) Why are the circles different sizes? (They represent different elements and each element has its own properties.) Notebooks: Students record observations of beakers in their notebooks. In the previous lesson, we studied elements. What is the definition of an element? (An element is a substance that cannot be broken down chemically into simpler substances; the building block of matter.) Look at the formulas. How many elements are in each formula? (Two elements in each formula, H and O.) Using the information you just determined about the circles for water, which circle do you think represents Hydrogen and how do you know? (Hydrogen is represented by the smaller circles; the little number in the formula tells you) You may need to explain that a subscript is the little number written behind and below the element symbol to represent the number of atoms in a formula. What is the difference in the chemical formulas for water and hydrogen peroxide? (An extra O or oxygen atom) Since the two substances have very similar physical properties, how could we tell which one is water and which one is hydrogen peroxide? Answers may vary, so guide students toward the idea of designing a way to test the properties of the substances. 7. Collect the beakers. Say: We will come back to these two substances later in the lesson. EXPLORE/EXPLAIN I Building Blocks of Matter II 1. Divide students into pairs. Distribute approximately 12 plastic interlocking blocks in three different colors to each pair of students. 2. Distribute a copy of the Handout: Building Blocks of Matter II to each pair. 3. Explain to the students that each block represents an element. Instruct the students to select a colored block to represent each of the three elements. Instruct the students to draw and color the blocks in the square that represent Suggested Days 1 (continued) Materials: plastic interlocking blocks (3 different colors, 12 per pair) glue or tape (per group) page 4 of 23

5 each element. 4. Say: Each block represents a different element and it cannot be broken down into anything smaller. Elements are the building blocks of matter. Choose a block to represent Iron, Oxygen, and Sulfur, then draw and color the blocks in the square that represents that element. Monitor and assist students as necessary. 5. Project the definition of a compound on the board: A compound is made from two or more elements that are chemically combined and is not separated by physical means into other substances. 6. Explain to students what a compound is: Say: Attachments: Handout: Building Blocks of Matter II (1 per pair) Instructional Notes: In Unit 03 students participated in an activity called Building Blocks of Matter. In Building Blocks of Matter II, students will complete the activity again, but with different elements. The activity is extended to assist students in understanding the difference between an element, a compound, and a mixture. Guide students through each definition and then assist pairs as necessary. Notebooks: Students copy definitions and affix handouts in their notebooks. A compound is made from two or more elements that are chemically combined and is not separated by physical means into other substances. Create the compounds using your blocks and draw and color your compounds in each square to represent Sulfate, Iron Oxide, and Iron Sulfide. Hint: Use the small numbers to help you determine how many blocks to use for each element. Monitor and assist students as necessary. 7. Instruct students to copy the definition of a compound in their science notebooks. (You may wish to have students copy the definition on the back of their handout.) 8. Project the definition of a mixture on the board: A mixture is a combination or more than one substance, but it does not create a new substance, and it can be separated. 9. Explain to the students what a mixture is: Say: A mixture is a combination of more than one substance, but it does not create a new substance, and it can be separated. A salad is an example of a mixture, because you can remove parts of the salad, such as tomatoes and onions from the salad. Mixtures can occur with just elements, with compounds, or with compounds and elements together. Create the mixtures on your handout, with your blocks, and then draw and color your mixtures in the squares. Monitor and assist students as necessary. 10. Instruct students to copy the definition of a mixture in their science notebooks. (You may wish to have students copy the definition on the back of their handout.) 11. After students complete the table on the handout, construct a structure with only one color of blocks and a structure that looks similar with two or more colors of blocks. 12. Explain to the students that one structure is made of only iron blocks and the other structure is made of multiple elements that are bonded together. Ask: What is the difference between an element and a compound? (Elements are made up of only one kind of block and compounds are made up of different blocks. ) What is the fewest number of blocks you could have to make a compound? (Two) Look at the structure made of only iron blocks, why is this not considered a compound? (It is made of a single element.) If I removed one block from the iron structure would it look similar to the rest of the structure? (Yes, because it is a block of iron.) page 5 of 23

6 If I separated one block from the compound structure, would it be similar to the larger structure? (No) Why not? Answers may vary. The block you removed is one element and it does not have the other colors or elements in it, etc. What is the difference between a compound and a mixture? (Compounds have elements bonded together and a mixture does not.) 13. Instruct students to affix the handout in their notebooks. EXPLORE II Compound Formulas Suggested Days 2 and 3 1. Divide students into groups. Inform students they will be building models of compounds and elements today. 2. Instruct one student from each group to gather five test tubes, a rack, and a small amount of the materials to place in each test tube. 3. Once materials have been distributed, instruct another group member to blow a small amount of air into a balloon and tie off the end. 4. Review the common name of the substances with the students. Ask students to observe the substances and create a T-Chart in their notebooks labeled Elements and Compounds. Then ask students to list each substance under the correct column: elements or compounds. (Note: the substances are all compounds, but do not tell the students at this time.) 5. Set the materials aside. 6. Distribute a set of the Teacher Resource: Compounds and Elements Matching Cards to each student. 7. Instruct students to cut apart the chemical names and formulas on the Matching Cards set. 8. Instruct students to match the chemical name of the compound cards to the correct chemical formula cards. Demonstrate how to match water to H 2 O. 9. Monitor students as they match the cards in their work area. Provide students with clues that might assist them in matching the chemical name to the formula. 10. Again, ask students to observe the substances. Ask students to review the definition for a compound. 11. Ask: A compound is made from two or more elements that are chemically combined and is not separated by physical means into other substances. After seeing the chemical formulas for each substance, do you need to revise your T- Chart to correctly list any of the substances as elements are compounds? How do you know? Accept appropriate answers and acknowledge all the substances are compounds and made up of elements. 12. Distribute the Handout: Compounds and Elements to each student. 13. Instruct students to glue the cards correctly on the Handout: Compounds and Elements. 14. Instruct students to complete the handout by writing both the symbol and the name of the elements found in each compound. Again, use water as an example. ( H = hydrogen; O = oxygen) 15. If students do not already have a copy of the Periodic Table of the Elements in their notebooks, distribute a copy to each student (see Advance Preparation). Instruct students to look for the substances on the Periodic Table of the Elements. Materials: test tubes (5 per group) test tube rack (1 per group) scoopulas (to dispense dry ingredients into test tubes, 2 per teacher) pipettes (to dispense wet ingredients into test tubes, 2 per group) table salt (small amount per group) chalk (1 piece per group) sand (small handful per group) water (small amount per group) honey (small amount per group) balloon (1 per group) Periodic Table of the Elements (see Advance Preparation, 1 per student) scissors (1 per student) glue or tape (1 per student) Attachments: Handout: Compounds and Elements (1 per student) Teacher Resource: Compounds and Elements KEY Teacher Resource: Compounds and Elements Matching Cards (1 set per student) Instructional Notes: These materials provide a concrete model to help students visualize the abstract concept of compounds and elements. Students are seeing a science concept in concrete form before working with the abstract concept of symbols to represent the same information. Students may struggle with the handout and matching cards. Encourage students to use clues in the compound names to identify elements they contain. Guide students as necessary. The compounds listed in this activity are also listed in the specificity as some that the students should recognize. Notebooks: Students draw T-charts and affix handouts in their notebooks. 16. Review the handout and make sure students have the correct elements listed. 17. Instruct the students to affix this chart into their science notebooks. 18. After the activity is complete: page 6 of 23

7 Ask: Were any of the substances pure elements? (No) How do you know? Answers may vary. None of the substances were found on the periodic table; all of the substances were made of more than one element, etc. What was the most common element in all of the compounds? (Oxygen) Were any of the elements metals? (Yes) How do you know? (Ca and Na were on the left side of the stair step on the periodic table.) Which element was a metalloid? (Silicon) How do you know? (It is found along the stair step on the periodic table.) Which compound had the most elements? (Fructose or honey) If I poured honey on the sand, would that be a compound? (No, it would be a mixture.) Why not? (The elements would be mixed together but you could separate them.) If I take the oxygen out of water, will it still be water? (No, you need hydrogen and oxygen to create water.) What would it turn into? Answers may vary. If it were separated, it would be hydrogen and oxygen would be left over. 19. Instruct groups to clean up materials for the next class, per your instructions. EXPLAIN II Compound Formulas Suggested Day 4 1. Ask: When you were identifying the chemical formulas and elements in the last activity, were you able to find the compounds on the periodic chart? (No) Why not? (Only elements are listed on the periodic table.) Did the chemical names give you a clue as to some of the elements that made up the compounds? (Some of names helped, but some names didn t include names of elements.) 2. Write Co and CO on the board and divide students into pairs. 3. Ask: What is the main difference between Co and CO? Answers may vary. Co is the element Cobalt and is found on the periodic table; CO has two elements, Carbon and Oxygen. CO is not on the periodic table. 4. Remind students that compounds are not found on the Periodic Table of the Elements. Have them review the definition of a compound in their notebooks and add this information: A compound has different properties than the original elements that formed it. Materials: beakers (1 with water and 1 with Hydrogen peroxide, from the previous ENGAGE activity, per teacher) plastic interlocking blocks (from previous activity, several per teacher)' Instructional Notes: The definition of a molecule for will not include diatomic elements. The concept of diatomic molecules such as the atmospheric gases O2, H2, N2, and the halogen gases will not be addressed. Misconception: Students may think that molecules have the same properties as the atoms from which they are composed. 5. Refer students to the observations they made concerning the two beakers of liquid used in the ENGAGE section. Display a pair of beakers filled with the two substances. 6. Using the blocks from the Building Blocks of Matter activity, create a structure that has two blocks of hydrogen and one block of oxygen. Explain to the students what the blocks represent. Write the formula for water on the board. 7. Say: Check For Understanding: Ask for student volunteers to summarize concepts using new vocabulary. Notebooks: Students write definitions and information in their notebooks. This chemical formula, H 2 O, is the formula for water. The letters tell me there is an element in the substance. When there is a little number written below the symbol, I know there is more than one particle of that element. It is called an atom. In this formula, there are two blocks of hydrogen, or two atoms of hydrogen. There is only one block of oxygen, or one atom of oxygen. page 7 of 23

8 Each element has its own atom and you will learn more about atoms in 8 th grade. 8. Project the following definition and instruct students to write it and the following information in their notebooks: A chemical formula is a combination of chemical symbols showing the atoms of which a substance is made and their proportions. A chemical formula is like the ingredients to make a compound. It tells you what elements to use and how much of each element you need. 9. Instruct students to write down H 2 O = 2 Hydrogen atoms and 1 oxygen atom as an example. 10. Instruct students to write H 2 O again and circle the two in the formula. Have them label the two as subscript. Then write the following definition in their notebooks. A subscript is a number written just below the line that shows how many atoms of an element are present in the formula. 11. Instruct students to draw the water structure made from blocks in their notebooks and label the blocks as hydrogen and oxygen. Have the students label the structure water molecule. 12. Instruct students to record the following definition in their science notebooks: A molecule is the smallest particle of a compound that can exist on its own and keep its properties. 13. Remind students that molecules may have different properties than the original elements. For example, CO 2 is composed of the solid element carbon and the oxygen gas and the molecule itself is a gas. (See instructional note on diatomic molecules.) 14. Close the class by conducting a check for understanding. 15. Write Co 2 on the board and ask the students to work with a partner to answer the question. Ask: Is this an element or a compound? Why? (Co 2 is an element because there is only one element, Cobalt, in the formula. There are two atoms of Cobalt.) 16. Give students time to discuss the answer to the question. Ask for volunteers to share their thoughts. 17. Clarify misconceptions and say: The subscript only changes how much of an element is present in the formula, but it does not make an element into a compound. A compound has to have more than one element. CO 2 is a compound called Carbon Dioxide. It has Carbon and also two atoms of Oxygen. Look for more than one capital letter to identify a compound. 18. Write the names, chemical formulas, and diagrams of the structure of water and hydrogen peroxide on the board again (see the ENGAGE section). 19. Direct students attention to the two beakers. Allow students to share the characteristics they observed earlier about the liquids. 20. Ask students to describe the similarities and differences in the formulas using the terms atoms, elements, compounds, and subscripts. EXPLORE III Water or Not Suggested Days 5, 6, and 7 page 8 of 23

9 1. Inform students that today they will be designing an investigation to determine if the liquid in beakers from our earlier activity is water or not. Materials: 2. Remind students that scientists use several steps to solve problems and document investigations. 3. Divide students into groups. 4. Distribute a copy of the Handout: Water or Not to each group. Distribute to each group two beakers with identical appearing liquids labeled X and Y (see the preparation for the ENGAGE activity). safety goggles (1 per student) beakers (small, 2 per group) water (small amount per group) hydrogen peroxide (small amount per group) raw potato slice (thin sliced, cut in half, see Advance Preparation, 2 halves per group) paper towels (several per group) 5. Say: During this lesson, we have determined that both of these liquids appear to be identical. Remember that one is water and one is hydrogen peroxide. Work with your partners to come up with a question to identify the problem or question we are trying to solve. The students should write something along the lines of Which beaker contains hydrogen peroxide and which beaker contains water? If you are familiar with peroxide, you will know that it will bubble if placed on a cut. Water will not. Record this information and any other observations you can make about the two substances in part two of the Handout: Water or Not. Students should record similar observations to those made during the Engage activity. In a few minutes you will work together to create a hypothesis and design an experiment to test it. What is a hypothesis? (It is a tentative explanation for an observation, or a scientific problem that can be tested by investigation. It is not just an educated guess.) We can write a hypothesis in an If, then format. Write the following on the board: Ex. If I water the plant, then it will grow. Every good experiment has an Independent Variable and a Dependent Variable. Can anyone give the class a definition of the two? Answers may vary. An Independent variable is what the researcher changes in an investigation and the dependent variable is what you observe or measure to determine if there was an effect. When writing a hypothesis the independent variable is written first and the dependent variable is written second. In our example the independent variable is the water for the plant. The dependent variable is the growth of the plant, what we will measure to see if the water had an effect. Underline water and label it Independent variable, then double underline grow and label it dependent variable. Attachments: Handout: Water or Not (1 per group) Safety Notes: Instruct students not to taste contents of either beaker. Remind them to be careful not to get any liquid on themselves. Review the MSDS for hydrogen peroxide safety and disposal. Instructional Notes: The material for this activity must be prepared fresh and not held over from the Engage activity. Hydrogen peroxide will deteriorate if left in light for several days, so you will need to replace it for Days 6 and 7. Potato slices may be stored in water to prevent oxidation. Students will not be ready to conduct their tests until Day 6. This may vary based upon the readiness level of your students. TEKS 6.2A require students to plan and implement comparative and descriptive investigations by making observations, asking well-defined questions, and using appropriate equipment and technology. Notebooks: Students are to draw the activity set up and write procedures and observations in their notebooks. Additionally, students affix the handout in their notebooks. 6. Remind students: It is not proper lab procedure to experiment on your body. You may not taste or place the liquids on your skin. You may not experiment on any person. I will give you a piece of potato. You have five minutes to try to figure out a way to tell these liquids apart. Do not test any materials yet, only brainstorm an idea for an experiment. 7. Give students five minutes to brainstorm for ideas to test the liquids. Allow each group to share their idea for an experiment with the class. Acknowledge all ideas. 8. Assist the class in identifying the independent variable (liquids) and the dependent variable (bubbles). 9. Ask the students to write their hypotheses on the Handout: Water or Not and then share with the class. An example would be, If I pour hydrogen peroxide on the potato, then it will make bubbles, or If I pour water on the potato, then it will not produce bubbles. 10. Instruct students to draw the setup for their investigation, and also to write the procedures to test the experiment on step 4 of the Handout: Water or Not. page 9 of 23

10 11. Remind them they are still not ready to test. 12. Assist the students in creating a data table to record their results. Ask: What is going to tell you if you have water or peroxide? (A lack of bubbles for water and bubbles for Hydrogen peroxide) Create a data table to keep track of our results. Will one trial be enough? (No, there should be multiple trials.) 13. Guide students to create a table such as the one below. In this example, students would indicate if bubbles were present for each trial with a yes or no. 14. Instruct the students to begin their experiment and remind them to record the data as they go through each trial. 15. Ask students to draw a conclusion about the results of their experiment. Say: Look at your results and draw a conclusion about hydrogen peroxide and water. Make sure that you say whether or not your hypothesis was correct. Explain why or why not. Do not change your hypothesis. If your hypothesis is not correct, it does not mean that your experiment is not helpful. Having an incorrect hypothesis is just as important and having a correct one. 16. Ask students to finish their handouts and to make sure they used complete sentences to make their experiment clear to others. 17. Ask the students to share their findings with the class. 18. Instruct groups to clean up their materials and return all items per your instructions. EXPLAIN III How it Works 1. Say: During our investigations, you learned that hydrogen peroxide is used as an antiseptic to wash cuts. One characteristic of hydrogen peroxide is that it will produce bubbles when applied to a wound. Water will not. The formation of bubbles is one sign that a chemical reaction has taken place. Suggested Day 7 (continued) Instructional Notes: A detailed explanation is provided but may be more than students need at this point. Students are not to be held responsible for the explanation of how hydrogen peroxide works, but the explanation is provided to satisfy the why questions students may ask. 2. Ask: Does anyone know how hydrogen peroxide makes the bubbles? Accept all answers. A more detailed explanation of what occurred is included below. Say: Hydrogen peroxide is 3% H 2 O 2 and 97% water. Blood and cells contain an enzyme called catalase. A cut or scrape contains both blood and damaged cells releasing catalase. When hydrogen peroxide comes into contact with the catalase, a chemical reaction occurs. The reaction of the catalase and hydrogen peroxide causes the peroxide to turn to water and release the extra oxygen as a gas. The bubbles are pure oxygen gas being created by the reaction. Potato cells are damaged when cut. They release catalase as well. This is why bubbles appear on the potato slice in the peroxide beaker page 10 of 23

11 and not the water beaker. EXPLORE IV Chemical Reactions Suggested Days 8 and 9 1. Explain to students they will be participating in a station activity over the next two days to investigate chemical reactions. 2. Say: Remember that compounds are two or more elements combined chemically to create a new substance. Today we are going to investigate to determine what evidence we can find to indicate a chemical change has occurred. 3. Set up lab stations prior to class. Stations can be set up all at once and groups will rotate though the stations over two days. 4. Divide students into groups and review station procedures with the students. This review should include safety concerns as well as station clean up issues. 5. Instruct students to sketch and label the activities in their notebooks. Additionally, students will summarize the procedures for each station and record detailed observations during each activity. 6. Monitor and assist groups as they move through each station. Use a signal to facilitate group movements between stations. Materials: triple beam balance (1 per Station A) resealable plastic bag (freezer weight, pint sized, 1 per group at Station A) calcium chloride (5 g per group at Station A) water (25 ml per group at Station A) thermometer (with backing, 1 per Station A) graduated cylinder (1 per Station A) timer (1 per Station A) safety goggles (1 per student, per Station B) triple beam balance (1 per Station B) cup (foam, 1 per Station B) baking soda (15 g, per group, per Station B) vinegar (25 ml per group per Station B) thermometer (with backing, 1 per Station B) graduated cylinder (1 per Station B) timer (1 per Station B) spoon (plastic, 1 per Station B) triple beam balance (1 per Station C) baking soda (2g, per group, per Station C) calcium chloride (2g, per group, per Station C) beaker (100 ml, 1 per Station C) water (40 ml, per group, per Station C) cups (clear plastic, 2 per Station C) spoon (plastic, 1 per Station C) safety goggles (1 per student, per Station D) apron (1 per student, per Station D) jars (baby food size, 2 per Station D) water (per Station D) food coloring (red, 1 bottle, per Station D) spoon (plastic, 1 per Station D) liquid bleach (a few drops, per group per Station D) pipette or eyedropper (1 per Station D) safety goggles (1 per student per Station E) balloon (1 per group, per Station E) funnel (plastic or paper, 1 per Station E) baking powder (15 ml per group, per Station E) vinegar (per Station E) plastic water bottle (1,500 ml, empty, 1 per Station E) Attachments: Teacher Resource: Evidence of Chemical Reactions (see Advance Preparation, 1 card per station) Instructional Notes: Set up lab stations prior to class. Stations can be set up all at once and groups will rotate though the two days. EXPLAIN IV Evidence of Chemical Change Suggested Day Facilitate a discussion of the results from the previous day s investigation. Ask students to report observations and changes in temperatures recorded. Write student observations on the board as students report them. Use the results to guide students to the conclusion that there were chemical reactions, and that those Materials: Periodic Table of the Elements (see Advance page 11 of 23

12 reactions produced evidence of chemical change. 2. Ask: What happens when we mix two substances and a new substance is created? Answers may vary. A compound is formed/a chemical change has occurred. 3. Say/Ask: During a chemical reaction, the bonds between atoms in a substance are broken. The atoms rearrange themselves and form bonds with new substance partners. There are different types of bonds and they hold atoms together. You will learn about the processes of bonding in high school science courses. What types of evidence did we see in our investigation? Answers will vary, but should include production of a gas (odor, bubbles), change in temperature, production of a precipitate, and change in color. Based on the previous investigation, what is a good definition of a chemical change? Answers may vary. A chemical change is when two substances come together and create something new; the new substance cannot be separated into the old substances. Chemical reactions involve a change in chemical makeup in the substances which we were investigating. You cannot easily get back your original substances because something new has been formed. Have you ever tried to take a fried egg and turn it back to its original state? The properties of the original substances are different than the properties of the new substances that are formed. 4. Instruct students to work with a partner to create a definition of a chemical change in their notebooks. Allow a few minutes for discussion and then ask for volunteers to share with the class. Attachments: Preparation, 1 per student, previously distributed) Handout: Elements, Compounds, and Evidence of Change (1 per student) Teacher Resource: Elements, Compounds, and Evidence of Change KEY Instructional Notes: Iron (Station A) is an element. The compound space should remain blank. The Evidence of Change box is for the documentation of the type of change that occurred when all the substances were mixed together. Misconception: Students may think molecules have the same properties as the atoms from which they are composed. Notebooks: Students list the four signs of a chemical reaction and a brief description of each in their notebook. Additionally, students affix their handouts in their notebooks. 5. Work with the class to formulate an appropriate definition for a chemical change. Encourage students to revise their definitions as appropriate. 6. Ask: How could we identify a chemical change? Accept all answers at this time; color change, temperature change, odor change, a precipitate is formed, or a gas is formed. 7. Say: There are several ways to tell if substances have undergone a chemical change when they are mixed together. Some evidences are: a change in odor/ production of a gas a substance disappears a change in form light or sound is given off This list is not complete. Sometimes a chemical change can look like a physical change. For example, two changes in form can be compared. If you tear paper it is a physical change, but if you burn paper, it is a chemical change. During a chemical change new substances are being created, where do you think the matter for the new substance comes from? Answers may vary. The new substances are created by rearranging the elements from the old substances. 8. You will have to know four indicators that are evidence that a chemical change has taken place. Write these in your notebooks. Production of a gas Bubbles form or an odor forms upon mixing substances together. Change in temperature It takes energy to break chemical bonds. When the reaction involves more bond breaking than bond making, the energy needed is absorbed from the surroundings. This makes the page 12 of 23

13 temperature cooler. If there is more bond making than bond breaking, extra energy is released. This makes the temperatureincrease. Production of a solid precipitate When mixing a pair of substances that dissolve in liquid, the sudden appearance of a solid that rains down (precipitates) into the bottom of the container is a sign that a reaction has occurred. Sometimes the particles are too small to settle to the bottom and just make the solution look cloudy. Change in color Every compound absorbs a characteristic set of colors of light. This color is like a fingerprint for that compound. If the compound changes, the color can change. 9. Distribute the Handout: Elements, Compounds, and Evidence of Change to each student. 10. Instruct students to use their periodic tables and their notes from the stations activities to fill in the table. 11. Instruct students to write the symbols for the elements in each substance, the chemical formula for the compound, the type of chemical change, and an explanation of what evidence there was for the change. 12. Monitor and assist as necessary. Students should affix the handout in their notebooks. ELABORATE Diagraming Change Suggested Day Orally or in writing, give the following instructions to students: Fold an index card vertically and then horizontally into fourths. Unfold the card and draw an oval in the center where the folds intersect. In the oval, write Evidence of Chemical Change. Draw lines on the folds to the point where they meet the oval. Materials: index cards (large, 1 per student) markers or colored pencils (per group) glue or tape (per group) Write one of the following labels near the top of each quadrant: color change, temperature change, a solid precipitate forms, or gas bubbles form. Draw a representation of each indicator of a chemical change in each quadrant. Affix the note cards to your notebooks. Instructional Note: Graphic organizers, such as with the Frayer Model style graphic, assist students in visualizing key concepts. 2. Instruct the students to write a paragraph in their notebooks, using the index cards they just made. The topic of the paragraph will be how they know a chemical change has occurred. Additionally, students should give an example of each type of evidence using the following sentence stem: A chemical change has occurred when I mix. I can identify a chemical change if I observe EVALUATE Performance Indicator Suggested Days 12 and 13 Grade 06 Unit 04 PI 01 Create a tabbed or layered book. On each tab, include the formula of a compound, elements, and number of atoms present in each compound. On the back of the book, write a summary that explains the evidence for a chemical change taking place as a new substance is formed. Standard(s): 6.2E, 6.5C, 6.5D ELPS ELPS.c.5B, ELPS.c.5F, ELPS.c.5G Materials: paper (see Advance Preparation, 5 half sheets per student) scissors (per student) staples, tape, or glue (per group) 1. Project the Performance Indicator on the board. Students will create a tabbed book including the elements noted in the Performance Indicator (see Teacher Resource: Creating a Tabbed Book). You may wish to list specific compounds on the board for students to choose from. Attachments: Teacher Resource: Creating a Tabbed Book 2. Share the Performance Indicator rubric or your expectations with students prior to students beginning the assessment. page 13 of 23

14 3. Students will create their tabbed book and then use their science notebooks for their summaries. The list of the four signs of chemical change is provided in the EXPLAIN IV Evidence of Chemical Change section. 4. Answer any questions students may have regarding the assessment. page 14 of 23

15 Building Blocks of Matter Element Compound Mixture Element Mixture O = Oxygen SO 4 = Sulfate O and S Compound Mixture S = Sulfur Fe 2 O 3 = Iron Oxide (Rust) SO 4 and FeS Element and Compound Mixture Fe = Iron FeS = Iron Sulfide H and CO , TESCCC 08/22/12 1 of 1

16 Compounds and Elements Common Name Chemical Name Chemical Formula Elements in Compound Exhaled breath Water Table salt Honey Chalk Sand 2012, TESCCC 08/22/12 page 1 of 1

17 Compounds and Elements KEY Common Name Chemical Name Chemical Formula Elements in Compound Exhaled breath Carbon dioxide CO 2 (C) Carbon (O) Oxygen Water Water H 2 O (H) Hydrogen (O) Oxygen Table salt Sodium chloride NaCl (Na) Sodium (Cl) Chlorine Honey Fructose C 6 H 12 O 6 Chalk Calcium carbonate CaCO 3 (C) Carbon (H) Hydrogen (O) Oxygen (Ca) Calcium (C) Carbon (O) Oxygen Sand Silicon dioxide SiO 2 (Si) Silicon (O) Oxygen 2012, TESCCC 08/22/12 page 1 of 1

18 Compounds and Elements Matching Cards Silicon dioxide Water Silicon dioxide Water Calcium carbonate Carbon dioxide Calcium carbonate Carbon dioxide Fructose Sodium chloride Fructose Sodium chloride C 6 H 12 O 6 SiO 2 H 2 O CO 2 NaCl CaCO 3 C 6 H 12 O 6 SiO 2 H 2 O CO 2 NaCl CaCO 3 Silicon dioxide Water Silicon dioxide Water Calcium carbonate Carbon dioxide Calcium carbonate Carbon dioxide Fructose Sodium chloride Fructose Sodium chloride C 6 H 12 O 6 SiO 2 H 2 O CO 2 NaCl CaCO 3 C 6 H 12 O 6 SiO 2 H 2 O CO 2 NaCl CaCO , TESCCC 08/22/12 page 1 of 1

19 Water or Not 1. Problem: Write a question to identify the problem. 2. Observations: Record everything you know about water and hydrogen peroxide and include similarities and differences. WATER HYDROGEN PEROXIDE 3. Hypothesis: If, then. 4. Experiment Set up and Procedures: Materials: Procedure: 2012, TESCCC 08/22/12 page 1 of 2

20 5. Identify the independent variable: 6. Identify the dependent variable: 7. Data: Create a table to record your data. Don t forget to label the table. (IV) (DV) (DV) (DV) 8. Conclusions: Summarize your findings here. Remember to state if your hypothesis was correct or incorrect and what this indicates about the experiment. 2012, TESCCC 08/22/12 page 2 of 2

21 Elements, Compounds, and Evidence of Change Substances - Station A Element(s) Compound(s) Evidence of Change CaCl 2 (calcium chloride) H 2 O (Water) Substances - Station B Element(s) Compound(s) Evidence of Change NaHCO 3 (baking soda) CH 3 COOH (vinegar) Substances - Station C Element(s) Compound(s) Evidence of Change CaCl 2 (calcium chloride) NaHCO 3 (Baking soda) H 2 O (water) Substances - Station D Element(s) Compound(s) Evidence of Change H 2 O (water) C 18 H 14 N 2 Na 2 O 8 S 2 (red food coloring) NaClO (bleach) Substances - Station E Element(s) Compound(s) Evidence of Change *NaHCO 3 (baking soda) * NaAlSO 4 (cream of tartar) * CaHPO 3 (dry acid) * C 6 H 10 O 5 (cornstarch) CH 3 COOH (vinegar) Baking powder is a mixture of several substances marked by * 2012, TESCCC 08/22/12 page 1 of 1

22 Elements, Compounds, and Evidence of Change KEY Substances - Station A Element(s) Compound(s) Evidence of Change CaCl 2 (calcium chloride) Ca, Cl CaCl 2 H 2 O (Water) H, O H 2 O Temperature change got hotter Substances - Station B Element(s) Compound(s) Evidence of Change NaHCO 3 (baking soda) Na, H, C, O NaHCO 3 CH 3 COOH (vinegar) C, H, O CH 3 COOH Temperature change got colder Substances - Station C Element(s) Compound(s) Evidence of Change CaCl 2 (calcium chloride) Ca, Cl CaCl 2 NaHCO 3 (Baking soda) Na, H, C, O NaHCO 3 H 2 O (water) H, O H 2 O Precipitate formed new substance formed Substances - Station D Element(s) Compound(s) Evidence of Change H 2 O (water) H, O H 2 O C 18 H 14 N 2 Na 2 O 8 S 2 (red food coloring) C, H, N, Na, O, S C 18 H 14 N 2 Na 2 O 8 S 2 Color change turned from red to clear NaClO (bleach) Na, Cl, O NaClO Substances - Station E Element(s) Compound(s) Evidence of Change Baking powder is a mixture of several substances marked by * *NaHCO 3 (baking soda) Na, H, C, O NaHCO 3 * NaAlSO 4 (cream of tartar) Na, Al, S, O NaAlSO 4 * CaHPO 3 (dry acid) Ca, H, P, O CaHPO 3 Formation of a gas bubbled * C 6 H 10 O 5 (cornstarch) C, H, O C 6 H 10 O 5 CH 3 COOH (vinegar) C, H, O CH 3 COOH 2012, TESCCC 08/22/12 page 1 of 1