Snail Variations - Lesson Plan
- Discuss any ground rules (like do not hurt any snails) then jump right in! Pass out the snails, hand lenses, rulers, and stop watches. Ask groups to spend a few minutes observing the features and behavior of the snails.
- When students have had enough time to study the snails, have them close the lids. Ask students what they noticed. In particular, focus on how individual snails differ from one another. Discuss both the physical and behavioral traits of the snails.
- Ask students how these different physical and behavioral characteristics could be measured. Discuss the difference between subjective (bigger, faster, smarter) and objective (4.5 cm, travels 8 cm/min, figures out a maze in 2 min) measurements.
- Challenge students to pick a snail trait to measure. They should write down a procedure for their test and record the result for each snail that they were given. Everyone in the group must agree on the procedure such that the results would be the same, no matter who conducted the test. That means that your procedure should describe exactly what to do as if you were describing how to conduct the test over the phone to a friend. For instance, if you want to measure “size”, do you measure weight or length or width or height? If you measure length, what do you do when the snail is hiding inside its shell? Do you count antennae or not? Do you use centimeters or inches?
- Give students time to choose a trait, agree on a procedure and record their data. Circulate among the groups to help students that are struggling. Groups that finish early should be challenged to design a second procedure – possibly with the requirement that if they already tested a physical trait, that their second test should be of a behavioral trait.
- When all groups have finished, have them close the lids again. Discuss different ways to graphically present the results – pie charts, histograms, line graphs, etc. Tell students that they will be given 5 minutes to prepare a presentation for the rest of the class. Their presentation should include:
- a description of their procedure
- a table of results for their population of snails
- a graphical presentation of their results