Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 1

Transcription

1 Density To Float or Not to Float? That is the Question! Grade Level or Special Area: Eighth Grade Science Written by: Aida Peterson, Clear Lake Middle School, Denver, Colorado Length of Unit: Twelve lessons (approximately 12 days; one day = 50 minutes) I. ABSTRACT In this unit, students will investigate density. They will learn how to calculate density of fluids and solids using mathematical equations. They will learn how to find density of regular and irregular shaped objects. They will learn the role of density in why things such as hot air balloons, submarines and fish, sink and float. II. OVERVIEW A. Concept Objectives 1. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). (adapted from Colorado Science Model Content Standards, Standard 2.1) B. Content from the Core Knowledge Sequence Science, 8 th grade, p Physics a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) The buoyant force on an object is an upward (countergravity) force equal to the weight of the fluid displaced by the object. b) Density = mass per unit volume c) Relation between mass and weight (equal masses at same location have equal weights) ii. How to calculate density of regular and irregular solids from measurements of mass and volume a) The experiment of Archimedes iii. How to predict whether an object will float or sink C. Skill Objectives 1. Students will take notes on Mass and Weight. 2. Students will take notes on Volume. 3. Students will take notes on Density and Buoyancy. 4. Students will use a graduated cylinder to measure the volume of liquids. 5. Students will use a triple beam balance to measure the mass of several objects. 6. Students will use a ruler to measure length. 7. Students will work in a cooperative group. 8. Students will make observations and collect data. 9. Students will manipulate variables in an experiment. 10. Students will analyze the results from an experiment. 11. Students will make predictions and test them. 12. Students will write a conclusion about what they have learned from the experiment. 13. Students will practice safety rules during a laboratory investigation. 14. Students will find the volume of different objects by displacement. 15. Students will use mathematical equations to calculate the volume of regular shaped objects. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 1

2 16. Students will use their notes and their laboratory investigations to answer questions on volume. 17. Students will demonstrate their understanding of the density unit by answering questions of the Density Calculation Worksheet. III. IV. BACKGROUND KNOWLEDGE A. For Teachers 1. Physical Science. Holt Science and Technology 2. ScienceSaurus: A Student Handbook B. For Students None RESOURCES A. List of laboratory materials needed for each lab is included before each lesson V. LESSONS Lesson One: Notes on Mass and Weight (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) Relation between mass and weight (equal masses at same location have equal weights) 3. Skill Objective(s) a. Students will take notes on Mass and Weight. B. Materials 1. Overhead projector 2. Transparencies of Notes on Mass and Weight, Appendix A (pp. 1 and 2) 3. Science notebook (students ) 4. Colored pencils or colored markers (students ) 5. Pencil, pen, ruler and eraser (student s supplies needed to take notes with) C. Key Vocabulary 1. Mass a measure of the amount of matter in an object 2. Kilogram the basic unit of mass in the metric system 3. Balance tool used to measure mass 4. Weight the measure of the pull of gravity on an object 5. Gravity a force of attraction between two bodies 6. Newton the basic unit of weight in the metric system 7. Spring Scale tool used to measure weight D. Procedures/Activities 1. Ask the students: what do you have in common with a sink or a shoe? Give students time to think and come up with some answers to share with the class. 2. If they don t come up with an explanation that has to do with matter, then tell them that everything is made of matter including people, sinks and shoes. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 2

3 3. Ask the students how we measure matter. Give the students time to think and come up with answers to share with the class. Guide them to come up with mass as the measurement of how much matter an object has. 4. Ask the students what is weight. Allow students time to come up with answers to share with the class. Ask them if an astronaut goes out to space, does his weight and mass change. Let them come up with answers to share. 5. Tell the students that today they will be taking notes on mass and weight, and the difference between them. 6. Ask the students to get out their science notebooks, pencil or pen, colored pencils or markers and their ruler and eraser. 7. Remind them that they should try to be as neat as possible in their notebook, so that they may use it later to get the information easily. 8. Remind them that in order to make it easier to access the information in their notes, the students will be skipping lines wherever there is spacing on the overhead notes, they will be writing their headings in color and they will be putting a box around each vocabulary word in color. 9. Allow the students to get their notebook and supplies ready. 10. Use transparencies of Appendix A to give the students the notes. 11. As you put the transparencies on the overhead, talk briefly about what the students are writing. 12. Allow the students to copy the notes. Remind them to use color and skip lines where appropriate. 13. Collect and grade the notebooks. E. Assessment/Evaluation 1. Collect and grade science notebook for neatness and completeness. Use Appendix M, Rubric for Grading Science Notebook, to grade the notes. Lesson Two: Lab Metric Measurement: Mass (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) Relation between mass and weight (equal masses at same location have equal weights) 3. Skill Objective(s) a. Students will use a triple beam balance to measure the mass of several objects. b. Students will work in a cooperative group. c. Students will make observations and collect data. d. Students will analyze the results from an experiment. e. Students will practice safety rules during a laboratory investigation. B. Materials (per group of four students) 1. One triple-beam balance mL graduated cylinder 3. Coin Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 3

4 4. Large paper clip 5. Rubber stopper 6. Weighing paper 7. Small scoop 8. Table salt mL beaker 10. Copy of Metric Measurement: Mass, Appendix B, pp. 1, 2 and 3 (one per student) C. Key Vocabulary 1. Mass a measure of the amount of matter in an object 2. Kilogram the basic unit of mass in the metric system 3. Balance tool used to measure mass D. Procedures/Activities 1. Pass a copy of Metric Measurement: Mass, Appendix B, pp. 1, 2 and 3 to each student. 2. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 3. While the students are reading their lab handouts, pass out a tray containing a triple beam balance, graduated cylinder, coin, paper clip, rubber stopper, weighting paper, small scoop, table salt and a beaker to each group of four students. 4. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 5. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how to use a triple beam balance to measure mass by grading their responses to questions in Appendix B, pp.1, 2 and 3 (Metric Measurement: Mass). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Three: Notes on Volume (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. How to calculate density of regular and irregular solids from measurements of mass and volume 3. Skill Objective(s) a. Students will take notes on Volume. B. Materials 1. Overhead projector 2. Transparencies of Notes on Volume, Appendix C (pp. 1 and 2) 3. Science notebook (students ) 4. Colored pencils or colored markers (students ) 5. Pencil, pen, ruler and eraser (student s supplies needed to take notes with) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 4

5 C. Key Vocabulary 1. Volume the amount of space and object occupies 2. Liter the basic unit of volume in the metric system 3. Graduated cylinder tool used to measure volume of a liquid 4. Meniscus the curve of a liquid in a graduated cylinder 5. Cubic centimeter metric unit used to measure volume of a solid D. Procedures/Activities 1. Ask the students what they think volume is. Let them come up with answers to share with the class. 2. Tell them that today they will be taking notes on volume, the units used to measure it and the tools used to measure it. 2. Ask the students to get out their science notebooks, pencil or pen, colored pencils or markers and their ruler and eraser. 3. Remind them that they should try to be as neat as possible in their notebook, so that they may use it later to get the information easily. 4. Remind them, that in order to make it easier to access the information in their notes, the students will be skipping lines wherever there is spacing on the overhead notes, they will be writing their headings in color and they will be putting a box around each vocabulary word in color. 5. Allow the students to get their notebook and supplies ready. 6. Use transparencies of Appendix C, pp. 1 and 2, to give the students the notes. 7. As you put the transparencies on the overhead, talk briefly about what the students are writing. 8. Allow the students to copy the notes. Remind them to use color and skip lines where appropriate. 9. Collect and grade the notebooks. E. Assessment/Evaluation 1. Collect and grade science notebook for neatness and completeness. Use Appendix M, Rubric for Grading Science Notebook, to grade the notes. Lesson Four: Lab Measuring Liquid Volume Using a Graduated Cylinder (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. How to calculate density of regular and irregular solids from measurements of mass and volume 3. Skill Objective(s) a. Students will use a graduated cylinder to measure the volume of liquids. b. Students will work in a cooperative group. c. Students will make observations and collect data. d. Students will practice safety rules during a laboratory investigation. B. Materials (per group of four students) 1. Red, blue, and yellow food coloring 2. Water 3. Three beakers 4. Six test tubes Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 5

6 5. Test tube rack mL graduated cylinder 7. Labels for test tubes 8. Copy of Measuring Liquid Volume Using a Graduated Cylinder, Appendix D, pp. 1 and 2 (one per student) C. Key Vocabulary 1. Volume the amount of space an object occupies 2. Graduated cylinder tool used to measure volume of liquids D. Procedures/Activities 1. Tell the students that today they are going to practice using a graduated cylinder to measure volume. Tell them that it is very important for them to be very good at measuring volume with the graduated cylinder. It is a skill that they will use all year in science. 2. Pass a copy of Measuring Liquid Volume Using a Graduated Cylinder, Appendix D, pp. 1 and 2 to each student. 3. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 4. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 5. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 6. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students skill in using a graduated cylinder to measure volume by grading the results in their Data Table in Appendix D, p. 2 (Measuring Liquid Volume Using a Graduated Cylinder). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Five: Lab Finding the Volume of an Irregular Shaped Object by Displacement (50 Minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. How to calculate density of regular and irregular solids from measurements of mass and volume 3. Skill Objective(s) a. Students will use a graduated cylinder to measure the volume of liquids. b. Students will work in a cooperative group. c. Students will make observations and collect data. d. Students will practice safety rules during a laboratory investigation. e. Students will find the volume of different objects by displacement. B. Materials (per group of four students) 1. Nail 2. Quarter Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 6

7 3. Screw 4. Rock 5. Marble 6. Graduated Cylinder 7. Beaker 8. Water 9. Copy of Finding The Volume Of An Irregular Shaped Object By Displacement, Appendix E, pp. 1 and 2 (one per student) C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Show the students a clear container with water inside it. Ask the students how they would measure the volume of the water inside the container. Let them come up with answers. Hopefully they will suggest using a graduated cylinder. 2. Show the students a box and ask them how they would find the volume of the box. Let them think of answers to share with the class. Lead them to talk about calculating the volume after measuring the length, width and height of the box. Now show them a rock and ask them how they would go about measuring the volume of the rock. Let them come up with answers to share with the class. 3. Tell the students that today they are going to practice using a graduated cylinder to measure the volume of an irregular shaped object (that is an object that is not regular in shape, like the rock). Tell them that they will use this skill in a later lab to calculate density. 4. Pass a copy of Finding the Volume of an Irregular Shaped Object by Displacement, Appendix E, pp. 1 and 2 to each student. 5. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 6. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 7. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 8. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how to find volume by displacement by grading their responses to questions in Appendix E, pp.1 and 2 (Finding The Volume Of An Irregular Shaped Object By Displacement). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Six: Lab Finding the Volume of a Regular Shaped Object (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content from the Core Knowledge Sequence Science, 8 th grade, p. 198 a. Density and Buoyancy i. How to calculate density of regular and irregular solids from measurements of mass and volume Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 7

8 3. Skill Objective(s) a. Students will use a ruler to measure length. b. Students will use a graduated cylinder to measure the volume of liquids. c. Students will work in a cooperative group. d. Students will make observations and collect data. e. Students will practice safety rules during a laboratory investigation. f. Students will use mathematical equations to calculate the volume of regular shaped objects. g. Students will use a triple beam balance to measure the mass of several objects. B. Materials (per group of four students) 1. Balance 2. Milk carton 3. Beaker 4. Graduated cylinder 5. Metric ruler 6. Single edge razor blade or cutting knife 7. Copy of Finding The Volume Of A Regular Shaped Object, Appendix F, pp. 1 and 2 (one per student) C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Tell the students that today they are going to practice using mathematical equations to find the volume of regular shaped objects. 2. Pass a copy of Finding the Volume of a Regular Shaped Object, Appendix F, pp. 1 and 2, to each student. 3. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 4. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 5. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 6. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how to use mathematical equations to find volume of regular shaped objects by grading their responses to questions in Appendix F, p. 2 (Finding the Volume of a Regular Shaped Object). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Seven: Volume Overview (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 8

9 i. How to calculate density of regular and irregular solids from measurements of mass and volume 3. Skill Objective(s) a. Students will use mathematical equations to calculate the volume of regular shaped objects. b. Students will use their notes and their laboratory investigations to answer questions on volume. B. Materials (per student) 1. Copy of Volume Overview, Appendix G, p.1 2. Calculator C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Tell the student that today they are going to show their understanding of what we have learned so far about volume by answering some questions. Tell them they may use their own notes and the labs they have done but that they will have to work on their own. 2. Pass out Volume Overview, Appendix G, p. 1 to each student. 3. Allow students time to work on the questions by themselves while you walk around the class and monitor their work. 4. Collect Appendix G to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of volume by grading their responses to questions in Appendix G, p. 1 (Answer Key is Appendix G, p. 2) Lesson Eight: Notes on Density and Buoyancy (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) The buoyant force on an object is an upward (countergravity) force equal to the weight of the fluid displaced by the object. b) Density = mass per unit volume c) Relation between mass and weight (equal masses at same location have equal weights) ii. How to calculate density of regular and irregular solids from measurements of mass and volume a) The experiment of Archimedes iii. How to predict whether an object will float or sink 3. Skill Objective(s) a. Students will take notes on Density and Buoyancy. B. Materials 1. Overhead projector 2. Transparencies of Notes Density and Buoyancy, Appendix H (pp. 1 and 2) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 9

10 3. Science notebook (students ) 4. Colored pencils or colored markers (students ) 5. Pencil, pen, ruler and eraser (student s supplies needed to take notes with) C. Key Vocabulary 1. Density the measure of the amount of matter that occupies a certain space 2. Buoyant force the upward force exerted on an object that is immersed in a fluid 3. Archimedes principle states that the buoyant force of a fluid on an object is equal to the weight of the fluid displaced by the object D. Procedures/Activities 1. Ask the students why they think that a rock sinks in water and a leaf floats on top of water. Let them come up with answers to share with the class. 2. Tell them that today they will be taking notes on density and buoyancy. 3. Ask the students to get out their science notebooks, pencil or pen, colored pencils or markers and their ruler and eraser. 4. Remind them that they should try to be as neat as possible in their notebook, so that they may use it later to get the information easily. 5. Remind them, that in order to make it easier to access the information in their notes, the students will be skipping lines wherever there is spacing on the overhead notes, they will be writing their headings in color and they will be putting a box around each vocabulary word in color. 6. Allow the students to get their notebook and supplies ready. 7. Use transparencies of Appendix H, pp. 1 and 2, to give the students the notes. 8. As you put the transparencies on the overhead, talk briefly about what the students are writing. 9. Allow the students to copy the notes. Remind them to use color and skip lines where appropriate. 10. Collect and grade the notebooks. E. Assessment/Evaluation 1. Collect and grade science notebook for neatness and completeness. Use Appendix M, Rubric for Grading Science Notebook, to grade the notes. Lesson Nine: Lab Density Diver Lab (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) The buoyant force on an object is an upward (countergravity) force equal to the weight of the fluid displaced by the object. b) Density = mass per unit volume c) Relation between mass and weight (equal masses at same location have equal weights) ii. How to calculate density of regular and irregular solids from measurements of mass and volume a) The experiment of Archimedes Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 10

11 iii. How to predict whether an object will float or sink 3. Skill Objective(s) a. Students will work in a cooperative group. b. Students will make observations and collect data. c. Students will manipulate variables in an experiment. d. Students will analyze the results from an experiment. e. Students will make predictions and test them. f. Students will write a conclusion about what they have learned from the experiment. B. Materials (per group of four students) 1. Plastic bottle with cap 2. Water 3. Medicine dropper 4. Copy of Appendix I, Density Diver Lab, for each student C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Ask the students what makes a fish be able to change its depth in the water. Allow the students to come up with answers to share. 2. Tell them today they will be doing an experiment to find that out. 3. Pass a copy of Density Diver Lab, Appendix I, to each student. 4. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 5. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 6. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 7. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how density determines whether objects float or sink by grading their responses to questions in Appendix I (Density Diver Lab). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Ten: Lab Full of Hot Air (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) Density = mass per unit volume ii. How to calculate density of regular and irregular solids from measurements of mass and volume iii. How to predict whether an object will float or sink 3. Skill Objective(s) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 11

12 a. Students will work in a cooperative group. b. Students will make observations and collect data. c. Students will manipulate variables in an experiment. d. Students will analyze the results from an experiment. e. Students will make predictions and test them. f. Students will write a conclusion about what they have learned from the experiment. B. Materials (per group of four students) 1. Two aluminum pans 2. Water 3. Metric ruler 4. Hot plate 5. Ice water 6. Balloon ml beaker 8. Copy of Full Of Hot Air, Appendix J, for each student C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Tell the students that today they will investigate the effects of temperature change on the volume and the density of a gas. 2. Pass a copy of Full of Hot Air Lab, Appendix J, to each student. 3. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 4. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 5. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 6. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how changes in temperature affect the volume and density of a gas by grading their responses to questions in Appendix J (Full of Hot Air Lab). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. Lesson Eleven: Density Calculation Worksheet (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) The buoyant force on an object is an upward (countergravity) force equal to the weight of the fluid displaced by the object. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 12

13 b) Density = mass per unit volume c) Relation between mass and weight (equal masses at same location have equal weights) ii. How to calculate density of regular and irregular solids from measurements of mass and volume d) The experiment of Archimedes iii. How to predict whether an object will float or sink 3. Skill Objective(s) a. Students will demonstrate their understanding of the density unit by answering questions of the Density Calculation Worksheet. B. Materials (per student) 1. Copy of Density Calculation Worksheet, Appendix K, pp. 1 and 2 3. Calculator C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Tell the students that today they will be answering some questions on their own to show how well they know how to calculate density. 2. Tell them they may use a calculator and remind them that when they are asked to show their work, they must show their work to get credit. 3. Pass out a copy of Density Calculation Worksheet, Appendix K, pp. 1 and 2 to each student. 4. Allow the students to work on their assignment and circle the room to monitor. 5. Collect the papers to grade. E. Assessment/Evaluation 1. Evaluate the students ability to calculate Density by grading their responses to questions in Appendix K (Density Calculation Worksheet). Lesson Twelve: Fluids, Force and Floating Lab (50 minutes) A. Daily Objectives 1. Concept Objective(s) a. Develop an awareness of examining, describing, comparing, measuring and classifying objects based on common physical and chemical properties (for example, states of matter, mass, volume, electrical charge, temperature, density). 2. Lesson Content a. Density and Buoyancy i. When immersed in a fluid (i.e. liquid or gas), all objects experience a buoyant force. a) The buoyant force on an object is an upward (countergravity) force equal to the weight of the fluid displaced by the object. b) Density = mass per unit volume c) Relation between mass and weight (equal masses at same location have equal weights) ii. How to calculate density of regular and irregular solids from measurements of mass and volume a) The experiment of Archimedes iii. How to predict whether an object will float or sink 3. Skill Objective(s) a. Students will work in a cooperative group. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 13

14 b. Students will make observations and collect data. c. Students will manipulate variables in an experiment. d. Students will analyze the results from an experiment. e. Students will make predictions and test them. f. Students will write a conclusion about what they have learned from the experiment. g. Students will use a triple beam balance to measure the mass of several objects. h. Students will use a ruler to measure length. i. Students will practice safety rules during a laboratory investigation. j. Students will find the volume of different objects by displacement. k. Students will use mathematical equations to calculate the volume of regular shaped objects. B. Materials (per group of four students) 1. Large rectangular tank or plastic tub 2. Water 3. Metric ruler 4. Small rectangular baking pan 5. Labeled masses 6. Metric balance 7. Paper towels 8. Apron for each student 9. Copy of Fluids, Force and Floating Lab, Appendix L, pp. 1 and 2 for each student C. Key Vocabulary No new vocabulary D. Procedures/Activities 1. Tell the students that steal is almost eight times denser than water, then how come a huge ship made of steal float on water like a ball filled with air? Let them come up with possible answers to share with the class. 2. Tell them that today they will be investigating the force that makes it possible for steal ships to float instead of sink. 3. Pass a copy Fluids, Force and Floating, Appendix L, to each student. 4. Group the students in groups of four. Allow the students to read the lab within their group to figure out what they will be doing. 5. While the students are reading their lab handouts, pass out a tray containing the items listed under Materials to each group of four students. 6. Allow the students to work on the lab in their groups while you circle around the room to check that students are on task and to answer any questions they may need answered. 7. Allow the students to answer the questions in the lab within their group. Then pick up the lab handout to be graded. E. Assessment/Evaluation 1. Evaluate the students understanding of how buoyant forces affect the floating and sinking of objects by grading their responses to questions in Appendix L (Fluids, Force and Floating). Use Appendix N, Rubric for Grading Science Labs, to grade the lab report. VI. CULMINATING ACTIVITY A. Appendix K Formal Assessment on Density Unit Density Calculation Worksheet Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 14

15 B. Appendix L Performance Assessment on Density and Buoyancy Unit Fluids, Force and Floating Lab VII. VIII. HANDOUTS/WORKSHEETS A. Appendix A: Notes on Mass and Weight B. Appendix B: Metric Measurement: Mass C. Appendix C: Notes on Volume D. Appendix D: Measuring Liquid Volume Using a Graduated Cylinder E. Appendix E: Finding The Volume of An Irregular Shaped Object by Displacement F. Appendix F: Finding The Volume of a Regular Shaped Object G. Appendix G: Volume Overview H. Appendix H: Notes on Density and Buoyancy I. Appendix I: Density Diver Lab J. Appendix J: Full of Hot Air Lab K. Appendix K: Density Calculation Worksheet L. Appendix L: Fluids, Force and Floating Lab M. Appendix M: Rubric for Grading Science Notebook N. Appendix N: Rubric for Grading Science Labs BIBLIOGRAPHY A. Peterson, M.F. An Introduction to Physical Science for the Ninth Grade. Bismarck, ND: Department of Public Instruction, B. Physical Science. Holt Science and Technology. Austin, TX: Holt, Rinehart and Winston, C. ScienceSaurus: A Student Handbook. Wilmington, MA: Great Source Education Group, D. The Nature of Science Activity Book. Prentice Hall Science. Englewood Cliffs, NJ: Prentice Hall, E. The Nature of Science Laboratory Manual. Prentice Hall Science. Englewood Cliffs, NJ: Prentice Hall, F. Williams, Tammy K. Science Experiments: Chemistry and Physics. Lewistown, MO: Mark Twain Media, G. 100 Reproducible Activities: Physical Science. Grand Rapids, MI: Instructional Fair, Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 15

16 Appendix A, page 1 Notes on Mass and Weight Mass a measure of the amount of matter in an object Kilogram (kg) the basic unit of mass in the metric system 1 kg = 1000 g Gram (g) is one thousandth of a kilogram 1 g = 1/1000 Kg = Kg 1000 g = 1 Kg Milligram (mg) one thousandth of a gram 1 mg = 1/1000 g = 0.001g 1000 mg = 1 g Triple Beam Balance the tool used to measure mass Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 16

17 Appendix A, page 2 Weight the measure of the pull of gravity on an object Gravity a force of attraction between two bodies The strength of the gravitational force between two objects depends on the masses of the objects and the distance between them. a) The greater the mass of the object, the greater its gravitational force. b) The greater the distance between two objects, the weaker the gravitational force between them. Newton (N) the basic unit of weight in the metric system Spring Scale the tool used to measure weight **The difference between mass and weight is that mass does not change, while weight changes depending on gravity.** (i.e. if you go to the moon, your mass will not change but your weight will). Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 17

18 Appendix B, page 1 Name: Period: Date: Metric Measurement: Mass Purpose: To practice the proper way to use the triple-beam balance to measure the mass of different objects Materials (per group): One triple-beam balance 100-mL graduated cylinder Coin Large paper clip Rubber stopper Weighing paper Small scoop Table salt 250-mL beaker Procedures: Before beginning, be sure that the riders are moved all the way to the left and that the pointer rests on zero. Part A Measuring Mass Directly 1. Place the coin on the pan of the balance. 2. Move the rider on the middle beam one notch at a time until the pointer drops below zero. Move the rider back one notch. 3. Move the rider on the back beam one notch at a time until the pointer again drops below zero. Move the rider back one notch. 4. Slide the rider along the front beam until the pointer stops at zero. The mass of the object is equal to the sum of the readings on the three beams. 5. Record the mass to the nearest tenth of a gram in Data Table 1. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 18

19 6. Remove the coin and repeat steps 2 through 5 using the paper clip and then the rubber stopper. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 19

20 Appendix B, page 2 Part B Finding Mass by Difference 1. Find the mass of an empty 250-mL beaker. Record the mass in Data Table Using the graduated cylinder, obtain 50 ml of water. (Remember to read the volume at the bottom of the meniscus) 3. Pour the water into the beaker and find the mass of the beaker and water. Record the mass in Data Table 2. Part C Measuring Out a Substance 1. Place a piece of weighing paper on the balance pan and find its mass. Record the mass in Data Table Add exactly 5 g to the value of the mass of the weighing paper and move the riders to this number. 3. Obtain a sample of the table salt from your teacher. Using the scoop, add a small amount of salt at a time to the paper on the balance pan until the pointer rests on zero. 4. Dispose of the table salt in the container provided by your teacher. Observations Coin Paper Clip Rubber Stopper Data Table 1 Object Mass (g) Data Table 2 Mass of Empty Beaker (g) Mass of Beaker with 50 ml of Water (g) Data Table 3 Mass of Weighing Paper (g) Mass of Weighing Paper and Table Salt (g) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 20

21 Appendix B, page 3 Analysis and Conclusions 1. What is the mass of 50 ml of water? 2. Which rider on the balance should always be moved first when finding the mass of an object? 3. What is the mass of the largest object your balance is able to measure? 4. What is the mass of the smallest object your balance is able to measure accurately? 5. After using your balance, how should it always be left? (Adapted from 1993 edition of Prentice Hall Science: The Nature of Science Laboratory Manual, p. 25) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 21

22 Appendix B, page 4 Metric Measurement: Mass (Answer Key) Analysis and Conclusions: 1. What is the mass of 50 ml of water? Should be close to, if not exactly, 50 grams 2. Which rider on the balance should always be moved first when finding the mass of an object? The largest mass (rider on the middle beam) 3. What is the mass of the largest object your balance is able to measure? 610 grams (check for sure that this matches your balance) 4. What is the mass of the smallest object your balance is able to measure accurately? 0.1 grams (again check that this matches your balance) 5. After using your balance, how should it always be left? With all the riders to the left and the pointer on the zero Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 22

23 Appendix C, page 1 Notes on Volume Volume the amount of space an object occupies Liter (L) the basic unit of volume in the metric system Milliliter (ml) one thousandth of a liter 1 ml = 1/1000 L = L 1000 ml = 1 L * Milliliters and liters are usually used to measure the volume of liquids. Graduated Cylinder the tool used to measure the volume of a liquid Meniscus the curve of a liquid in a graduated cylinder When you measure the volume of a liquid you must look at the bottom of the meniscus. Cubic centimeters (cm 3 ) the metric unit used to measure the volume of solids Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 23

24 Appendix C, page 2 A cubic centimeter is equal in volume to a cube that measures 1 cm by 1 cm by 1 cm The volume of a cubic centimeter (cm 3 ) is exactly equal to the volume of one milliliter 1 cm 3 = 1 ml Calculating the volume of a rectangular solid Volume = Length x Width x Height If you use cm as your unit of measurement, then the unit for volume is (cm x cm x cm) which is equal to cm 3 If you use m as your unit of measurement, then the unit for volume is (m x m x m) which is equal to m 3 Calculating the volume of a cylindrical solid Volume = π r 2 x Height Where pi (π) is equal to 3.14, and r is the radius of the circle that makes up the two opposite sides of the cylinder Calculating the volume of a sphere Volume = 4 π r 3 3 Where pi (π) is equal to 3.14, and r is the radius of the sphere Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 24

25 Appendix D, page 1 Name: Period: Date: Measuring Liquid Volume Using a Graduated Cylinder Purpose: To develop skill in measuring with a graduated cylinder To use the metric system in measuring volume Materials (per group): Red, blue, and yellow food coloring Water Three beakers Six test tubes Test tube rack 50-mL graduated cylinder Labels for test tubes Procedures: 1. Label the test tubes from A through F. 2. Fill three beakers with water. Add a few drops of food coloring to each beaker so that you have one beaker of red water, one of blue water, and one of yellow water. 3. Into test tube A measure 19 ml of red water. 4. Into test tube C measure 18 ml of yellow water. 5. Into test tube E measure 18 ml of blue water. 6. From test tube C measure 4 ml and add it to test tube D. 7. From test tube E measure 7 ml and add it to test tube D. Mix. 8. From the beaker of blue water measure 4 ml and add it to test tube F. Then from the beaker of red water measure 7 ml and add it to test tube F. Mix. 9. From test tube A measure 8 ml of water and pour it into test tube B. From test tube C measure 3 ml and add it to test tube B. Mix. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 25

26 Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 26

27 Appendix D, page 2 Observations and Conclusions Complete the data table below by listing the final colors in each test tube. Give the total amount of water in each test tube. Test Tube Color of Water Total Amount of Water A B C D E F Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 27

28 Appendix D, page 3 Measuring Liquid Volume Using a Graduated Cylinder (Answer Key) Observations and Conclusions Complete the data table below by listing the final colors in each test tube. Give the total amount of water in each test tube. Test Tube Color of Water Total Amount of Water A Red 11 ml B Orange 11 ml C Yellow 11 ml D Green 11 ml E Blue 11 ml F Violet 11 ml (adapted from 1993 edition of Prentice Hall Science: The Nature of Science Activity Book, p. 65) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 28

29 Appendix E, page 1 Name: Period: Date: Finding the Volume of an Irregular Shaped Object by Displacement Purpose: Materials: To practice finding the volume of objects using displacement Nail, Quarter, Screw, Rock, Marble, Graduated Cylinder, Beaker, Water Procedures: 1. Use the beaker to pour water into the graduated cylinder. 2. Sit the graduated cylinder flat on the tabletop. 3. Bend over so that the water level is at eye level and look for the meniscus. (The meniscus is the curve of water. Read your measurement at the bottom of the meniscus) 4. Record the number in milliliters of liquid (to the nearest one-half ml) in your Data Table. This step will be done before each object is lowered into the liquid. Record the liquid volume in the box under Beginning Volume (second column). 5. Once a beginning liquid volume has been measured, gently lower an object into the liquid. The amount that the water rises (amount of water displaced) is equal to the volume of the object. 6. Read the new volume at the meniscus and record it in the Data Table under Volume of Liquid and Object for the object (first column). 7. To calculate the volume of the object alone, subtract the Beginning Volume from the Volume of Liquid and Object (subtract Column 2 from Column 1). 8. Repeat the above steps for each of the remaining objects. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 29

30 Appendix E, page 2 Observations Data Table Object Screw Nail Quarter Rock Marble Volume of Liquid and Object (ml) Beginning Volume (liquid) (ml) Volume of Object (ml) (Volume of Liquid and Object) - (Beginning Volume) = Volume of Object Analysis and Conclusions 1. Why is it necessary to recheck the starting volume of liquid before each object is put in? 2. What kind of error would result if you read the liquid volume at the top of the meniscus rather than the bottom of the meniscus? 3. How does this measuring volume by difference method compare with measuring volume using math for these odd-shaped objects? (adapted from Laboratory Skills by Mark Twain Media, Inc., pp. 7 and 8) Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 30

31 Appendix E, page 3 Finding the Volume of an Irregular Shaped Object by Displacement (Answer Key) Analysis and Conclusions 1. Why is it necessary to recheck the starting volume of liquid before each object is put in? It does not matter what volume you start with every time, but it is crucial to check the starting volume before each object is put in. Since you are calculating the difference between two measurements, if you do not recheck your volume before starting, you will get a wrong answer, and your results will not be reliable. 2. What kind of error would result if you read the liquid volume at the top of the meniscus rather than the bottom of the meniscus? You would always get a higher volume than your actual value. 3. How does this measuring volume by difference method compare with measuring volume using math for these odd-shaped objects? Measuring volume by difference is much more effective than trying to find the volume using mathematical equations in the case of odd shaped objects. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 31

32 Appendix F, page 1 Name: Period: Date: Introduction: Purpose: Materials: Finding the Volume of a Regular Shaped Object A three dimensional object occupies a certain amount of space. The space occupied may be measured and expressed in cubic units with the superscript 3 above the unit name (ex: cm 3 or m 3 ) Regular geometric shapes have an algebraic formula that may be used to calculate their volume. In this activity you will use a graduated cylinder to measure a quantity of liquid. This quantity is recorded in milliliters (ml). For our purposes one ml of water is equal to one cm 3. Also, one gram of water occupies the volume of one ml or one cm 3. To achieve skill in measuring, calculating and recording volumes in metric system balance, milk carton, beaker, graduated cylinder, metric ruler, and single edge razor blade or cutting knife Procedures: 1. Cut a half-gallon milk carton to half size. 2. Place the carton on the balance. Record the mass of the carton in the Data Table. 3. Add 500 grams of water to the carton. Record the mass in the Data Table. 4. Use the ruler to measure the height of water, the width of the carton, and the length of the carton. 5. Calculate the volume of the water. (Volume = L x W x H) Record your calculated value of the volume of water in the Data Table. 6. To find the total volume of the water, pour the water into a graduated cylinder. You may have to empty and refill the cylinder several times to get the total volume of water. Record your measure value of the volume of water in the Data Table. Eighth Grade, Density To Float or Not to Float? 2004 Colorado Unit Writing Project 32