Phase: | During/Explore/Explain |
Activity: | Introduce the activity by asking the students if they know why a Hermit Crab needs a new shell. After giving students time to respond, explain that Hermit Crabs don't have shells of their own and must use the abandoned shells of other creatures. The crabs have soft abdomens and the hard shells protect their abdomens. When a Hermit Crab starts looking for a new shell, they check it out with their claw. The crab uses its claw to make sure the shell is the right size and nothing is inside. Then they slip into the new shell. Watch the Amazing Crabs Shell Exchange video. Explain to the students that now they will design and construct their own shells for a Hermit Crab. Students will partner up to complete the challenge. Pass out the rubrics (one per student). Each pair will design and construct a shell for a Hermit Crab that will withstand the weight of the Dixie cup holding 20 pennies (or any predetermined amount of weight). The large cotton ball will be the "Hermit Crab" and must fit inside the shell when the shell is held up and must stay inside the shell without any help (tape or hands). Students should be able to remove the "Hermit Crab" by gently tugging on it. After a predetermined amount of time, I usually give my students 30 minutes to work on their shells, have the students complete the exit slip. |
Assessment Strategies: | Use the exit slip and the Crab Shell STEM Challenge Rubric to ensure students can provide evidence to support an argument that the external structures of a Hermit Crab function to support survival, growth, behavior, and reproduction. |
Advanced Preparation: | Exit slip - one copy for each student Crab Shell STEM Challenge Rubric - one copy for each student Teachers will need to gather the materials for the Mobile Home Crab Shell Challenge: egg cartons aluminum foil toilet paper rolls paper plates pipe cleaners tape styrofoam cups rubber bands bubble wrap newspaper card stock large cotton balls (crab) Dixie cup with 20 pennies |
Variation Tips (optional): | The teacher can determine the weight and time limit as well as change the required materials for this challenge. |
Notes or Recommendations (optional): |
Keywords and Search Tags: | animal behaviors, external structures, Hermit Crabs, organisms |