Which Picks Up More?

Challenge students to design another experiment with paper towels. Ask students to identify the variables and describe the experiment. Students can design and carry out their own experiment. As students discuss the design of the new experiment, keep in mind that they will be looking for the relationship between two variables while holding other variables fixed. For example, instead of investigating the relationship between the type of paper towel and the area of the spot of water while keeping other variables fixed, students can explore the relationship between the type of liquid and the area of a spot while keeping other variables, including the type of paper towel, fixed. Students may be interested in finding the relationship between the type of paper towel and its strength. They can measure strength by counting how many masses can be placed on suspended wet paper towels before they break.

If students try a new experiment, you can assess their abilities to collect, organize, graph, and analyze data.

• Are they able to communicate clearly which variables they have chosen to study?
• Did they use an appropriate data table?
• Did they clearly show their results on a graph or diagram?
• Are they able to make predictions or generalizations based on their data?

Since this lesson comes early in the year, you will need to help the students structure their experiments. We hope that students will become more independent as the year progresses and they become more familiar with the TIMS Laboratory Method. Assess their abilities now so you can document their growth throughout the year.