Objectives:
Students will use a game simulation to experience change in a population due to selective pressure.

Students will explain how environmental factors put selective pressure on populations.

Sponge: Using a Punnett square, calculate the possibility of a normal heterozygous (Bb) mouse and a blind (bb) mouse having blind mice as offspring.

Anticipatory Set:
-Review sponge and genetics vocabulary – return the genetics quiz, give them opportunity to correct quiz and earn back points
-Q: What are some traits elephants pass on to their offspring?

Guided Practice:
- Note: populations change as individuals with a helpful trait reproduce more than others (ex: walkingsticks & camouflage)
- Read “Tall, Gray, and Tuskless” & “More Tuskless Elephants Than Ever” from Life Science Daybook (p. 76-77)
-Q: If there were 100 male Asian elephants in a population, how many of them would normally have tusks?  What about in a population that has been exposed to poaching?

Independent Practice:
-“Elephant Walk” Activity: use jellybeans to model how poaching affects elephant populations – students act as poachers and eat the white (tusked) jellybeans, whereas as red (tuskless) jellybeans get returned to the bag and reproduce

Making Meaning:
-DEFINE “selective pressure” (abiotic or biotic factor that affects the survival of particular organisms in a population)
-Connect back to walkingsticks [discussion]:
-Q: What selective pressure affected the walkingstick population?
-Q: In what way did the walkingstick population change over time?
-Q: How are the populations of elephants and walkingsticks similar? [as time permits, complete a box and T]

Closure:
When a trait disappears from a population, is it gone for good, or can it come back?

Homework: "Bikini Bottom Genetics 2" due Friday