Early in the year we do a unit in science on rocks and minerals. One of the best ways I have found to teach this is using cupcakes with several yummy ingredients. A student teacher I had several years ago came to me with this idea (she found it online) and we ran with it.
The cupcake of course represents the rock and the ingredients are the minerals (hence rocks are made up of minerals). We made a list of the things (ingredients) it takes to make a cupcake. We made an anchor chart, then I had my students picture a cupcake and pretend it's a rock. We discussed what it took to make a cupcake (rock) and the students were able to make the connection that the rock is made up of minerals, just as a cupcake is made up of ingredients.
The students are given a mini cupcake that I made with vanilla cake mix (I tried marbled, it didn't work well), chocolate chips, sprinkles (MANY, MANY sprinkles of all different kinds). The students have a graphic organizer where they predict what the inside of the cupcake looks like, then they take a "core sample" of the rock using a clear straw. This allows the students to see what is inside the rock. Next they make another prediction of what is inside the rock, they draw a picture and explain for both predictions. As a class we cut the cupcakes open and discuss the minerals, the ones that we can see and the ones that we can't (eggs, flour, etc.). The students then discuss with their partner or groups how the rocks are made and make connections with the cupcakes and write them down on their graphic organizer. I have used a graphic organizer I found online and have had the students just fold a sheet of paper in fourths, and fill in each space accordingly. It is ALWAYS a success! Let me know if you try it and how it works out for you and your kiddos!