Plan force vs. deformation investigation

4.A Plan an investigation, identifying controls to keep constant, and carry out the investigation to produce data to serve as the basis for evidence to develop a mathematical model for the relationship (pattern) between the amount of force applied to an object and the amount it deforms.

Look for students to do the following in the planning of the investigation:

identify the independent variable as the amount of force applied to an object,

identify the dependent variable as the amount of deformation in the object, and

identify control variables, including where the force is applied and how much of the object overlaps the two supports (bricks) in each test.

If students are struggling with the ideas of variables, you may need to review some examples from previous investigations they have done in prior years. OpenSciEd units will have multiple examples to draw from in the following units:

OpenSciEd Unit 6.2: How can containers keep stuff from warming up or cooling down? (Cup Design Unit)

OpenSciEd Unit 6.3: Why does a lot of hail, rain, or snow fall at some times and not others? (Storms Unit)

OpenSciEd Unit 7.1: How can we make something new that was not there before? (Bath Bombs Unit)

OpenSciEd Unit 7.3: How do things inside our bodies work together to make us feel the way we do? (Inside Our Bodies Unit)

OpenSciEd Unit 7.4: Where does food come from, and where does it go next? (Maple Syrup Unit)

Remind students that we have a way to measure the amount of push by reading the amount of newtons on the push-pull spring scale. Ask for ideas about how to measure how much the object bends or deforms. Help students narrow in on the idea of recording the height of the beam before and after they push on it.

Discuss some things that would be important to keep constant in the investigation and add them to the experimental setup diagram. If students don’t suggest the placement of the object and the scale as things to keep constant, ask if the location of the spring scale on the material would affect the results and if the distance between the bricks and the amount of overlap of the material on the bricks would affect the results. Suggest that all groups test their objects in the center of the beam and make sure that their beams overlap the bricks by the same amount. A 2- or 3-cm overlap is suggested. Whatever you pick as a class, write the measurement on the anchor chart. Have students record these variables to keep constant on their Independent, Dependent, and Controlled Variables handout.

Post and save a copy of this anchor chart for students to refer to in this unit and future units.✱

Assign groups their materials to test. Have students record which material you assigned them to test above their data table on Deformation Results. The different options are as follows: a single wood stirrer, two wood stirrers stacked together, a single Styrofoam strip, or two Styrofoam strips stacked together. Tell groups to replace their materials with extras of these if after a test, it shows evidence of permanent deformation but has not yet cracked or broken into separate pieces.

Distribute Investigation Procedures to students. Project slide C. Tell students to use the procedure described on the Investigation Procedures handout to record the data from their investigation on the Deformation Results handout. Give students a couple of minutes to look through the procedure and then ask if there are any questions.