30 minutes

Students will investigate how shells are made.


Students will use plasticine or play dough to investigate how shells are made. Each student will also require a bamboo skewer or similar.

You will need some different shells for students to look at and compare.

A simple play dough recipe is provided in Teacher Resource Sheet: Play Dough Recipe.


  1. Engage students in a discussion as to where they think shells come from.  Pass around a variety of different types of shells.  Do animals make their shell, or do they shift shells?
    • Animals, with the exception of hermit crabs, make their own shells! If you look closely at a shell you can see the growth rings on it. These are from where the animal has added new pieces to its shell as it grows.  This is why you find shells of all different sizes on the beach.
  2. Look at all of the shells again, this time looking for the growth lines on the shells.
  3. Provide students with plasticine or play dough. Ask them to make a long, thin cone of plasticine or play dough.
  4. Start with the pointed end and coil your plasticine cone around the wooden skewer. Make sure the coils touch each other. This is what animals that live in these shells do… but much slower!
  5. Investigate whether you can make a shell like an abalone. Where are its growth rings and how would its shell become larger?


shells, hermit crabs, abalone