Tree Stump Middle School Application: Challenge Powerful Classroom Assessment (PCA) Published by the Science Learning Team of the Washington Office of the Superintendent of Public Instruction on December 30, 2008. Copyright 2008 by Washington Office of the Superintendent of Public Instruction (OSPI) All rights reserved. Educational institutions within the State of Washington have permission to reproduce this document. All other individuals wishing to reproduce this document must contact OSPI. 1 December 30, 2008
Tree Stump Directions: Use the following information to answer questions 1 through 10. Brian had to move a loose stump from a hole in his backyard. The stump was too heavy to lift. While solving this problem, Brian recorded the stages of his design process as follows. Problem: Lift a heavy stump out of a hole. Gather Information: A 1-Newton force could lift a 4-Newton weight when a meter stick is used as a lever, as shown in the Lever System diagram. Explore Ideas: Use a long lever to lift the heavy stump. Pull the stump up a ramp. Lift the stump with a pulley. Get more people and all lift the stump at once. Plan Summary: Use a long shovel as a long lever and a rock as a fulcrum because the rock is strong enough to hold up the shovel and tree stump. 2 December 30, 2008
Steps to do the Plan: 1. Move the rock close to the stump. 2. Put the shovel blade under the stump and rest the handle on top of the rock, as shown in the Diagram of Solution. 3. Push down on the end of the shovel handle while keeping the shovel blade under the stump and the shovel handle on top of the rock. Diagram of Solution: Test Solution: Apply a force to the Shovel Lever System by pushing down on the end of the shovel handle. Measure the height of the lifted stump. Test Results: The stump was lifted 4 centimeters above the ground. 3 December 30, 2008
1 Which of these lever systems is similar to the Shovel Lever System? o A. o B. o C. o D. 4 December 30, 2008
2 When Brian was trying to lift the stump with the shovel, he accidentally let go of the handle and the stump fell back in the hole. Which statement describes the stump s energy as it falls? o A. The potential energy and the kinetic energy of the stump decrease. o B. The potential energy and the kinetic energy of the stump increase. o C. The potential energy of the stump increases as the stump s kinetic energy decreases. o D. The potential energy of the stump decreases as the stump s kinetic energy increases. 3 Before Brian could lift the stump out of the hole, he had to cut the tree roots that had grown into the soil. What is a life function of roots for a living tree? o A. Roots transport carbon dioxide from the soil for photosynthesis o B. Roots deliver mineral nutrients from the soil to the tree. o C. Roots hold soil in place to prevent erosion. o D. Roots allow the tree to take in oxygen. 5 December 30, 2008
4 In which diagram below does the stump have the greatest potential energy? o A. o B. o C. o D. 6 December 30, 2008
5 Explain how the Shovel Lever System, shown in the box, allows Brian to lift the heavy stump. In your explanation, be sure to: Identify the lever and fulcrum in the Shovel Lever System. Describe how the lever and fulcrum allow Brian s input force to lift the stump. You may use words, labeled pictures, and/or labeled diagrams on the diagram below. 7 December 30, 2008
6 The lever system shown in the Lever System diagram below is a model of the tree stump, shovel, and rock. If this model were used to test possible solutions to Brian s stump problem, which part of the model would indicate how much force is required to lift the stump out of the hole? o A. The meterstick o B. The spring scale o C. The fulcrum under the meterstick o D. The weight to the left of the fulcrum 8 December 30, 2008
7 Brian could have used a shorter, 3-foot-long shovel to lift the stump instead of the longer, 5-foot-long shovel. Describe how using a shorter shovel would change the solution to the problem of lifting the stump In your description, be sure to: Describe how the shorter handle changes the amount of force needed to lift the stump. Describe how the problem of lifting the stump could be solved using the shorter shovel and the rock. You may use words, labeled pictures, and/or labeled diagrams on the diagram in the box. How the shorter handle changes the amount of force: How the problem of lifting the stump could be solved using the shorter shovel and the rock: 9 December 30, 2008
8 Which lever system would require the least input force from Brian? o A. o B. o C. o D. 10 December 30, 2008
9 Brian pushed down with the same amount of force in the four places marked A, B, C, and D on the diagram below. Applying force at which point on the shovel handle transfers the most force to the stump? o A. Point A o B. Point B o C. Point C o D. Point D 11 December 30, 2008
10 Brian s neighbor had an even heavier loose stump to move out of a hole. Brian tried his Shovel Lever System, but the stump was too heavy. They had some other materials shown in the diagram below. Using some or all of the materials shown, describe how you would design a way of lifting the heavier stump. Be sure to describe the following stages of your design process: Gather Information: Describe the information needed and how to collect that information. Explore Ideas: Describe several ideas, including any useful scientific concepts. Plan Summary: Write a summary of the plan, including reasons for choosing this solution. Steps to Do the Plan: Write the steps, including all the materials used in the Plan Summary and in the Diagram of Solution. Diagram of Solution: Make a labeled diagram. Test Solution: Describe the process to measure or observe how well this solution may solve the problem. Problem: Lift a heavy stump with some boards, bricks, and/or posts Gather Information: Explore Ideas: 12 December 30, 2008
Plan Summary: Steps to Do the Plan: Diagram of Solution: Test Solution: 13 December 30, 2008