This Rocks! Author: Sara Kobilka Institute for Chemical Education and Nanoscale Science and Engineering Center University of Wisconsin-Madison

Transcription

1 This Rocks! Author: Sara Kobilka Institute for Chemical Education and Nanoscale Science and Engineering Center University of Wisconsin-Madison Purpose: To learn about the rock cycle and the role that weather plays in the movement and shaping of the land Learning Objectives: 1. Learning the 3 types of rocks and 3 processes that make the rock cycle. 2. Explore the role weather plays in shaping the land. Next Generation Science Standards (est. 2013): PS2.B: Types of Interactions (partial) ESS2.A: Earth s Materials and Systems ESS2.C: The Roles of Water on Earth s Surface Processes (partial) Grade Level: 3-8 Time: 45 min Materials: Paint Trays (one per group) Soil Optional- sand and small rocks Plastic cups Ruler or meter stick (must be longer than the width of the paint tray), one per group Small rulers Sugar cubes Small containers with a lid that sugar cubes can be shaken in Sheets of paper Irons (old ones that you don t plan to use on clothes are best) or hot plate Wax paper Masking tape Crayons Plastic knives Containers of ice Optional- samples of igneous, metamorphic and sedimentary rocks plus magnifying glasses Safety: Make sure students are very careful around the hot iron and do not touch it. Pre-Activity Preparation: Make a circular hole in the bottom of half of the plastic cups ~1/2cm diameter.

2 Peel the paper off of all of the crayons. You will likely want to make extra bags of crayon shavings in case students struggle with that part of the rock cycle activity (especially if you are working with younger students). It is easiest to use a peeler to shave the crayons. Cut pieces of wax paper ~ 15cm x 15cm Introduction: The Earth has many systems including the geosphere (solid and molten rock, soil and sediments), the hydrosphere (water and ice) and the atmosphere (air). These different systems interact with one another to shape the surface of our planet. If students have already studied weather, this activity helps to transition to studying the geosphere. The first two activities help students begin to think about the impact that water and wind can have on the soil and rocks. Procedures: 1. Erosion Table a. Have the students pour soil into the paint tray. They should put in enough soil that the entire angled part of the tray has soil at least 1 cm deep while the flat bottom does not have any soil. Students should gently push on the soil that it lies flat (if they pack it too hard, this activity won t work as well). b. Position the ruler over the highest end of the paint tray so that there is a 1 inch gap between the edge of the ruler and the top edge of the tray. Then place the cup with the hole in the bottom so it balances between the ruler and the tray, allow water to drip out the hole and into the top of the tray (see picture below) ruler cup soil c. Ask the students what they think will happen when they pour water into the cup with the hole in it. Where will it end up? How will it get there? Have students write their answer on the worksheet. d. Have one student slowly pour water into the cup with the hole. The water will make its way through the soil, carving a path to the bottom. e. Ask the students why the water wants to end up in the lowest part (gravity). f. Have them closely observe what causes the water to curve to one side or another. The water is taking the path of least resistance so if it encounters are large piece of soil, it will try to go around it. Ask them what land feature or features this reminds them of. Some may be reminded of how a river or stream twists and turns. Others may think of a valley or the Grand Canyon. The bottom of the tray is like the ocean, where all of the soil (sediment) is

3 being deposited (hence the process is called deposition), as in the case of the mouth of a river. This area is called a delta. If your site is located near a delta, point on this location to the students. g. Have students draw a picture of what the water path through their erosion table looks like on their worksheet. h. Ask the students what they think will happen if they pour a second cup of water. Will the water take the same path as before or a different path? Will the valley they ve created stay the same or will it get deeper. i. Have a different student slowly pour water into the cup with the hole. j. Optional- Give the students an opportunity to further manipulate the landscape and water flow by adding areas of sand or rocks. You can also give the option of moving the cup to see what type of flow it creates. Encourage the students to make one change at a time and predict what will happen. Be sure that they not only explain what they think will happen but why they think it will happen. 2. Wind Erosion In the erosion table activity we saw how water can change the land. Another way that weather can have an impact on the rocks around us is through wind. a. Give each student a sugar cube. b. Using the ruler, have them measure one side of their cube and write it on the worksheet. c. Give the students a small container with a lid and have them put their sugar cube into the container. Have student add 2 more sugar cubes and place the lid on tightly. d. Instruct the students to shake the container vigorously for 1 minute. While they re doing this lay a sheet of paper in front of each student. e. After the minute ends, have them remove the lid and carefully pour the contents of the container onto the center of the paper. f. Have them make observations about how the sugar cube has changed. On the worksheet, they should write down their observations including measurements of any larger pieces that remain. Get students to think about how their movement (shaking the container) was like the wind blowing sand or rocks around. As the sand and rocks hit each other, they are weathered down into small and smaller pieces. g. Have students pour the sugar back into the container and keep their paper for the next activity. 3. Rock Cycle The last 2 activities focused on one process in the rock cycle, weathering/erosion. This next activity will show the other 2 processes that help transform rocks into the 3 main types. a. Optional- Begin by showing students samples of igneous, metamorphic and sedimentary rocks. Have them make observations about the shape, texture and makeup of each type of rock. Give the students magnifying glasses to help with their observations.

4 b. Lay a piece of wax paper in front of each student on top of the sheet of paper used for the sugar activity. c. Tell students that, in order to start making rocks, they need to create small pieces of material call sediments. Just like shaking up the sugar cubes gave them small sugar crystals, they will need to take something larger and make smaller pieces. In this case, they will be starting with crayons. d. Using plastic knives, have students shave off pieces of crayons onto their wax paper. Remind them that they are doing one of the processes in the rock cycle, weathering/erosion. You may want to provide students extra shavings if they are struggling. Students can use multiple colors of crayons. e. Once they have a small pile of shavings (~ the size of half a golf ball), have them observe the shape of the sediment pieces. Are they all the same? Where do they think they would find sediments in the real world? (refer back to the erosion table and where the water pushed the soil) Explain that, for this activity, these will act as small sedimentary rocks. f. Have students fold up the sides of their wax paper so that the sediments are trapped on the inside. Use a small piece of masking tape to tape the little package closed. g. Explain that they are now going to do another one of the processes in the rock cycle. You will be adding pressure to change the rocks into a different type of rock. h. Have students start by smashing the package between their hands and pressing hard for 1 minute. If they have a difficult time doing this, they can put the package on the ground and gently press on it with their foot. i. Have students remove the tape and open the package. They will find that their shavings have compressed into a rock. This is called a metamorphic rock. Have students make observations about how the rocks have changed because of the pressure. Are the colors still separate or have the mixed together? j. Explain that there is a third process of changing rocks and this involves so much heat the rocks melt. k. Lay down an extra sheet of wax paper on top of the original sheet or refold the sheet into a package if you want a fatter rock. The group leader should take an iron and press down on the wax paper, melting the wax inside. Be careful not to burn the table or leave the iron on the wax paper for too long. After the wax has turned to liquid, the group leader should lift the rock and the paper surrounding it using a glove or tongs. It can then be put in a container with ice, under an ice pack or simply left untouched for a couple minutes to cool. l. Once it has sufficiently cooled, return the rock to the student so they can observe the changes that have occurred. Are the colors still separate or have the mixed together? This rock is now an igneous rock. Ask the students where on earth they think it would be warm enough to melt rocks (underground or in a volcano). When lava cools, it forms an igneous rock. m. Explain to students that if they were to complete the cycle, they could take this new igneous rock they made, and scrape it with the knife to break it

5 down into sediments to make a sedimentary rock. Have them fill out the rock cycle on the worksheet. The cycle should look like this: Sedimentary Weathering/ erosion Pressure Igneous Discussion: There are many cycles in science. When studying weather, students learn about the water cycle. In the case of rocks, the rock cycle is the means of transforming from one form to another. The version of the rock cycle that the student are filling out is simplified. In actuality, rocks can move through the cycle in multiple ways. For example, a metamorphic rock and be broken down into a sedimentary rock or melted into an igneous rock. Evaluation: Name the 3 different types of rocks How do rocks can change from one type to another? How can weather change the Earth s surface? Activities adapted from: Heating Metamorphic This lesson is the product of the Institute for Chemical Education and the Nanoscale Science and Engineering Center at the University of Wisconsin-Madison. This Material is based upon work supported by the National Science Foundation under grant number DMR SCIENCountErs Lessons are licensed under a Creative Commons Attribution- NonCommercial 4.0 International License. Permissions beyond the scope of this license may be available by ing ice@chem.wisc.edu.