Rock Types & The Rock Cycle

Transcription

1 Rock Types & The Rock Cycle Grade Level Subject Areas Skills Duration Setting Vocabulary Montana and [National] Standards Addressed Goal Objectives 4, but can be adapted to higher levels Geoscience, general science (making observations and classifying rocks) Observation and classification of rocks, group work, oral presentation minutes (depending on if extension is used) Classroom Rock classification, observations 2.2 [B] classify objects based on physical characteristics 4.1 [D] model and explain the internal structure of the earth, and its constructive and destructive forces 4.2 [D] differentiate between rock and mineral types and how they were formed This activity demonstrates the rock cycle. Students will learn how rocks on Earth are recycled to create other rocks, which may be of a different type (and look completely different) than the original due to natural processes. Students will: Be able to group rocks into one of three groups: sedimentary, igneous, and metamorphic and will know how each forms and what distinguishes it from the other types Understand how sedimentary, igneous, and metamorphic rocks are connected via the rock cycle and describe how each can be formed into another type by certain processes Materials Crayon shavings (I used a pocket knife to shave crayons) Aluminum foil Hot plate or candle Tweezers Hammer Granola bars ones with chocolate chips and other pieces work best since the chocolate can melt.

2 Colored pencils and paper Background Procedure This activity uses crayons and granola bars as an analogy for how rocks form and how each type of rock can turn into another type of rock via processes in the rock cycle. In the Rock Observation and Grouping Lesson students were able to group rocks by color, feel, hardness, etc. This activity allows students to group rocks using a common grouping used by geologists, pertaining to how rocks are formed. 1. Give the students an introduction: Ask students: How do rocks form? (BRAINSTORM) - pressing together and gluing of sediments sedimentary This often happens in layers, so many (but not all) sedimentary rocks have bands/lines. Sometimes you can see the sediment grains, like in sandstone. - heat up rock and melt it like in a volcano igneous These rocks are the bubbly ones or glassy ones you see with volcanoes. They can also look spotted because different types of crystals are different sizes. Usually, the bigger the crystal, the longer it had to form (the slower it cooled). - being squeezed and heated metamorphic These rocks can also look banded because they ve been squeezed. They may also look like they have been folded. 2. Perform demonstrations using crayons and granola bars: Sedimentary Rocks: 1) Give students crayon shavings of each color- explain that these are their minerals in the form of sediment. 2) Place crayon shavings of different colors onto a piece of aluminum foil and have them sketch their sediments. 3) Wrap the foil and explain that we will be applying pressure to these sediments using a hammer. Have them hypothesize what will happen to the sediments (write in their books). 4) Hammer packets. 5) Carefully unwrap packets and have them redraw their rock what happened to it? We just make a sedimentary rock! Igneous Rocks: 1) Make aluminum foil packet from above into a boat use boat to see magma form, otherwise, refold packet, but cover in an additional piece of aluminum foil to prevent leakage of melted

3 wax. 2) Use tongs/tweezers to hold the packet over a candle or hot plate. HOLD IT A LITTLE BIT ABOVE THE FLAME! 3) While wax is melting, hypothesize what the rock will look like after it gets heated and cooled. 4) Place aluminum foil on the desk and let it cool. 5) Once it s cooled, look at and sketch the newly formed igneous rock. Metamorphic Rocks: 1) Give each student a trail mix/granola bar. DO NOT UNWRAP! 2) Demonstrate what the bar looks like (unaltered) at the front of the class and have students draw it. All the pieces are like a sedimentary rock, where the oatmeal and chocolate chips and raisins are pieces of sediment. The honey(?) is the glue holding it together. 3) Tell students we are going to apply pressure and heat to their bars and to hypothesize what will happen to them. Write down their observations in their notebook. 4) Have students squeeze the wrapped bar, where they are also applying heat to it with their hands. 5) Unwrap the bar and draw their new metamorphic rock. 6) Have them eat their metamorphic rock. Assessment Extension Student participation in answering questions related to the analogies between crayon shavings and granola bars to rock types and processes that form rocks (pressure, heat, glue ). Also homework assignment/handout (see attached file) can be used as an assessment. I also prepared a rock cycle poster which I had the kids assemble I printed out words and phrases (see Figure 1 below) and had students put arrows pointing to rock types based on the descriptors of how different rocks form and how all rock types are connected. This was reinforced by giving students the handout as a homework assignment to complete without the help of the poster to copy answers from.

4 Figure 1. Pictures of water, volcanoes, etc. can be added to show how some processes occur. Homework assignment (next page) answer key: 1. Minerals, pressure, time 2. Minerals, heat, time 3. Minerals, pressure, heat, time 4. Igneous 5. Erosion/weathering points to sediments, melting points to igneous, pressure and heat points to metamorphic, and compaction/lithification points to sedimentary.

5 Name: Rock Types & The Rock Cycle: MINERALS + PRESSURE + HEAT + TIME = ROCKS! Using the words in the math problem above, fill in these blanks: 1.,, and are important for making sedimentary rocks. 2.,, and are important for making igneous rocks. 3.,,, and are important for making metamorphic rocks. 4. The difference between heating in igneous rocks and metamorphic rocks is that igneous / metamorphic (circle one) rocks are heated until they melt. 5. Draw arrows on each line to show how any rock can turn into a different rock type: