Natural selection: individuals vary; more are born than survive; those best suited to the environment are more likely to survive and reproduce, passing on their alleles. Over generations the population changes. Individuals don't change to suit the environment.
After a bushfire, the ground is black. A few years later, a beetle population on it is darker than before. No beetle changed colour.
Individuals vary. This lesson: what happens to that variation when some individuals are more likely to survive.
Make your prediction first. Help opens once you've locked it in.
You are a bird. Click beetles to eat them (as fast as you can, like a hungry bird). Then press Survivors breed. Compare the bar charts: the start and the latest generation.
Hunt and breed for three generations.
Use the board. This ticks when you get there.
In your book: explain natural selection for the beetles using the words variation, survive, reproduce, inherit and generations.
Put the steps of natural selection in order.
Let the birds hunt for a few generations, darken the ground, and keep going until six generations.
Use the board. This ticks when you get there.
Write one sentence: "At first I thought… Now I think… because…"
Revision summary
Students model natural selection as predators, explain it in steps, reject the idea that individuals change because they need to, and connect it to common ancestry and the tree of life (AC9S10U02, node 2, a hinge node). About 26 minutes.
Open the teacher guide: answers, solutions, slides and a worksheet.
A concept tutorial for introducing or revising the idea; it pairs well with the classic peppered moth story and a paper-dots predation game. Set the width with ?width=minimum, typical (default) or wider.
The hinge misconception is need-driven change ("the beetles turned dark to hide"). The Engage question puts it directly, and the board never changes a beetle's colour.
Closing the loop with Year 7: the last three Explain questions take natural selection to common ancestry (a branching tree, not a ladder; DNA similarity tracks how recently species shared an ancestor) and back to the Year 7 Kingdoms lesson, where students met the idea that kingdoms sort by features, not relatedness. This supports the descriptor's "explain past and present diversity" and prepares the evidence for evolution.
Board notes: half the beetles are eaten each generation; survivors breed back to the full number, and each offspring gets the average of two parents' colours plus a small random change (a stand-in for many genes and mutation). The automatic birds favour beetles that contrast with the ground but also eat some at random. Results vary from run to run; with student hunting, a student who clicks randomly sees little change, which is a good discussion point.
Saying the population changed, not the beetles. When a student says the beetles adapted, ask whether any one beetle changed its own colour.
Stretch: Why does natural selection take many generations, not one?
Support: Give the five steps on cards to order before writing.
Later: evidence for evolution (fossils, comparative anatomy, DNA) in more depth, and speciation, if your program covers them. Year 7 Kingdoms is the earlier half of the classification thread.
In class: the paper-dots predation game on newspaper and plain paper; antibiotic resistance as a case study.