This is a great activity to introduce or reinforce the concept of the difference between elements, compounds, and mixtures.
In this activity students rotate in groups throughout the 15 stations. They must draw what the see at each station in the cart provided. Then they must classify each model as either an element, a compound, a mixture of elements, a mixture of compounds, or a mixture of elements and compounds. (You could modify this to make it easier for lower grades to just classifying an element, compound, or mixture). I use gumdrops to make my models but you can use whatever materials you like.
The students really enjoy this activity because it gets them out of there seats and it is a concrete way to "see" an abstract concept.
This includes a Teacher's Guide, ways to modify the activity to fit your needs, and an extension activity to challenge some students if you like. It includes all student worksheets and charts/tables.