How Dense

7th grade Integrated Science Standard 2, Objective 2 Title: How Dense? Description: Students will be given a selection of substances and asked to put them in order from least dense to most, similar to layering in Earth. They must justify their choices and be able to write the rationale down. They may make measurements using the equipment of their choice. Materials: suggestions for substances: clay, water, vegetable oil, rock, brick, metal bar, aluminum can, glass marbles or slides, ceramic tile, gravel, cotton, Styrofoam etc. Time Needed: 50 minutes Background Information: Students should have had experience finding the density of substances in a variety of ways. They can Procedures: 1. “Hook” the students with a demonstration of density such as a lava lamp or “dancing spagetti” (broken spagetti noodles in Sprite). Ask students to explain why the bubbles in the lamp move or why the spagetti rises and falls (air bubbles attach to it, lowering the density). 2. Explain to students that they will be building a model of Earth and it’s layers with the materials you have provided. They must choose a material for each layer of Earth and justify why they placed it in that location. 3. Show students the materials you have provided and give them the student sheet. Students should be placed in working groups of 3-4. 4. Go over the introduction and allow students to work and fill in the data. Each group needs to decide on a common plan. 5. Have each student group present their ideas to the class. Scoring Guide: 1. Students participate and test materials………………………………….4 2. Students design a logical plan to test materials………………………..4 3. Students accurately test materials………………………………………..4 4. Students report their findings honestly and relate them to Earth……..4

Student Sheet

Name____________________

Title: How Dense? Introduction: Scientists think that Earth has layers because it was once made from a ball of molten liquids and hot gases. As it cooled, the substances settled into layers based on their density. In this activity, you will choose and test materials to make a model of the density of Earth’s layers. You will need to decide how to find out the density of the materials and which would best model each layer of Earth. Materials: Procedures: 1. Write down the steps you will take to find the density of each substance that you have chosen. Remember to write clearly enough so that another student could follow your directions. 2. Test each substance and record your findings in the data. 3. Identify each substance by which layer of Earth you think it would best model. Be sure you have a substance for each layer: Inner Core, Outer Core, Mantle, Crust, Oceans and Atmosphere 4. Be prepared to tell the class about your decisions. Data: Substance

Procedures

Density

Earth Layer