Lesson 4

Why Do Piloses Have Thinner Trunks Nowadays?

A trait variant can be beneficial, harmful, or neither to an individual. A beneficial trait variant makes it more likely an individual will be healthy, survive, and have many offspring. Over many generations, the beneficial trait variant will become more common. This process is called natural selection.

Big Idea

Students hear a story about animals called piloses in which the proportion of individuals in a population with thinner trunks increases over many generations. They reason about the sequence of events involved in the change. The class agrees on a framework called the 6 Key Steps that they might be able to use to explain how any animals and plants could change over time.

Activity

Materials to Have Ready

For each student

Notebook page 9
A set of story strips (black text)
A set of labels that highlight the key steps in natural selection (blue text)
Glue sticks

For the class

The 6 Key Steps Classroom Poster
6 Key Steps piloses story template (handmade on paper) if unable to project it from the Slide Deck onto a Smartboard or equivalent