Dear Students:

In an attempt to create something edible this summer, I tried making Rice Krispy Treats. Not surprisingly they didn’t turn out. I’ve since been told that the marshmallows you use are more important than you might think. If the marshmallow you use does not have sufficient density, your finished product will be too hard (take it from one who knows).

I am providing you these samples of marshmallows in an effort to find the best brand to use in my future Rice Krispy Treat creations. Please check the mass to volume ratio for each of the samples provided you. Compare the same size marshmallows to each other, and also check to see how the different sizes compare to each other. Report your data in table form and organized into graph(s) as well.

Notes to the teacher:

This lab examines the linear relationship between mass and volume for a particular object. By storing the mass and volumes into lists on the TI-83 students will use the linear regression capabilities of the calculator to see the line of best fit. By graphing the data, students will see another meaningful application of ratios and slope. Analyzing the data students will consider range, linear regression, and calculated single values (m/v=d) versus average values derived from the slope of the line of many points. Some basic error analysis will also be discussed. You will need:

• 2 or 3 different brands of marshmallows.

• 100 ml Graduated cylinders and water if you will measure the volume by water displacement. (You probably could use Pr²h if you can smash the TR into a more regular shape. Then, you will need rulers.)

• 2 or more electronic or triple beam balances (borrow them from the science dept)

When doing this lab, I’d prefer not to tell the kids anything else; let them figure out what to do and what the significance of the ratio is...some of the kids will have learned about density, previously. Of course, you could have a class brainstorming session to determine what should be done and what exact procedures to use. You could talk about density being m/v before beginning the activity, or not.