I created this lab to help students understand not only the differences between solids, liquids, and gases but elements, compounds, and mixtures. Students love anything hands-on, especially when it involves food. My students are much better at comparing and contrasting states of matter and types of matter after completing this activity.
I recommend using the cereal with little colored balls (rabbit on the box). You can use other types of cereals as long as the shapes are different and the colors are solid like those fruity cereal rings.
You can include a bowl of cereal at each table for students to snack on while working on the activity for an extra level of excitement! Of course, I always discuss lab safety and the rules about tasting/eating in the lab.