Unit 07 · Natural Selection
The big ideas here are how populations change over time: the evidence for evolution drawn from fossils, anatomy, and molecules; natural selection acting on variation; Hardy–Weinberg as a model of when allele frequencies hold or shift; and how speciation and phylogeny chart life's branching history. Mastery means explaining the mechanism precisely and correcting the common misconceptions about it.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Mechanism of natural selection | Cannot state how selection works. | Names variation and survival; logic is incomplete. | Explains variation, fitness, and differential reproduction. |
| Evidence for evolution | Offers no supporting lines of evidence. | Cites one type of evidence. | Connects fossil, anatomical, and molecular evidence. |
| Hardy–Weinberg reasoning | Cannot apply the model. | Uses the equations but misreads the conditions. | Calculates frequencies and states when equilibrium holds. |
| Speciation & phylogeny | Cannot read a phylogenetic tree. | Reads trees but explains speciation loosely. | Interprets trees and explains how isolation drives speciation. |
| Common misconception correction | Repeats "need" or "trying" language. | Spots a misconception but cannot fully correct it. | Identifies and corrects teleological misconceptions clearly. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“There’s natural variation in beak size; in the drought the bigger beaks survive because they can crack the hard seeds, and those birds breed. The population shifts — nothing chose to change, the environment just selected what was already there.”
“The strong ones survive. Animals adapt to their environment over time because they need to.”
You demonstrate this unit through data and tree-reading tasks plus oral checks where you explain the mechanism and correct misconceptions in your own words. A criterion is mastered when you can reason from evidence, not recite a definition.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.