Designing+Force+Experiments

**Language Objective:** We will share information in cooperative learning interactions.
 * Content Objective:** We will design an experiment that tests the effects of force on an object.

**ENGAGE:** 10 minutes


 * Review Scientific Method
 * 1) How many variables should we have in our question?
 * 2) How many times should we test our experiment to make it reliable?
 * 3) Why do scientists do experiments?

**EXPLORE:** 40 minutes
 * Model the Scientific Method (DANA Center Force and Motion pg. 169-174)
 * 1) Set up the fishing line/balloon system for the students to see.
 * 2) Ask: What is a force?
 * 3) Ask: What force will move this balloon along the fishing line?
 * 4) Blow up the balloon to 20 cm. (Measure the diameter of the balloon with a measuring tape.)
 * 5) Ask students to predict how far the balloon will travel at 20 cm in diameter.
 * 6) Experiment.
 * 7) Record results.
 * 8) Are those results reliable? What could we do to make them more reliable?
 * 9) Repeat balloon experiment twice more at 20 cm diameter and record results.
 * 10) We have observed that a balloon with a diameter of 20cm goes a certain distance. What variable could I change to make the balloon go a different distance?
 * 11) What hypothesis can you make about the diameter of the balloon and the distance it will travel?
 * 12) Change balloon diameter to 35 cm and experiment three times and record results.
 * 13) Change balloon diameter to 50 cm and experiment three times and record results.
 * 14) What patterns do we see in our data?
 * 15) What conclusion can we make?

**EXPLAIN:** 5 minutes
 * Friction -- a force, or resistance, caused by two objects rubbing together.
 * Increased friction will slow an object down
 * Decreased friction will allow an object to move more freely

**ELABORATE:** 40 minutes


 * Students experiment (Materials from Models and Designs Foss Kit)
 * 1) Students will build a go-cart according to directions from the teacher.
 * 2) Attach binder clip close to one end of a long stick (not right on the end).
 * 3) Attach one wheel to one end of a medium stick.
 * 4) Slide the metal loops of the binder clip attached to the long stick onto the end of the binder clips onto the medium stick so that the loops are facing down and the mouth of the black clip faces up.
 * 5) Attach a wheel to the other end of the medium stick.
 * 6) Attach a binder clip close to the other end of the long stick (not right at the end).
 * 7) Attach one wheel to one end of a short stick.
 * 8) Slide the metal loops on the end of the binder clips onto the short stick so that the loops are facing down.
 * 9) Attach a wheel to the other end of the short stick.
 * 10) Cut two rubber bands. Tie the ends together to make a rubber band string.
 * 11) Remove one wheel from the medium stick and secure the rubber band into the grove at the end of the medium stick.
 * 12) Replace the wheel.
 * 13) Cut two more rubber bands and repeat for the other side.
 * 14) Anchor both rubber band strings into the grove at the far end of the long stick.
 * 15) Draw a light pencil mark on one of the wheels attached to the medium stick.
 * 16) Turn the wheels attached to the medium stick backwards (away from the system) five times (count the number of times the pencil mark goes around), put it on a flat surface and let it go.
 * 17) Students will record the distance of three trials for their go-cart.
 * 18) Brainstorm. What are some things that could change the distance the go-cart travels?
 * number of times the rubber band turns
 * the length of the sticks
 * the number of rubber bands attached to each side
 * the surface the cart is rolling on
 * 1) Students must choose ONE variable to change about their experiment.
 * 2) Students should make a hypothesis about how they think their change in variable will change the distance the go-cart travels.
 * 3) Allow time for students to make the change, then repeat the experiment 3 times and record data.
 * 4) What patterns did you notice?
 * 5) What is your conclusion?
 * Rubric