One of the the misconceptions that students tend to keep coming back to when learning about evolution is the idea that organisms evolve “into” one other (so to speak) rather than branching off from common ancestors. This is why you commonly hear the questions, “Did we evolve from monkeys?” or, “If we came from monkeys then why are monkeys still around?”.
In order to attempt to address this misconception, last semester I started doing an activity as part of my evolution unit to help students better understand phylogenetic trees and evolutionary relationships. The activity is in three phases:
- Phase 1 – students examine “passport” cards that different runners got during a race. Every time the runners took a different path (which here is a metaphor for a new trait or branch of evolution), they got a different stamp. The students reconstruct the race map based on the passport stamps.
- Phase 2 – students examine different animal cards with different traits printed on them that each of the animals have. They fill in a chart listing which traits go with which animal. (These traits happen to match the stamps the runners had on their passports as well).
- Phase 3 – students make a phylogenetic tree for the animals out of pipe cleaners that is a 3D representation of the race map they drew in phase 1.
I love this activity because by the time students are at phase 3 I start to hear a lot of “oh ok” and “oh I get it” going around the room. I think that even though most of my students could answer a multiple choice question about a phylogenetic tree without this activity, they don’t truly understand what the branch points represent until they actually go through the process of building one.