A 7th-grade science lesson exploring the scale of Earth's biological history through a video-guided timeline and a hands-on 'toilet paper timeline' activity. Students learn about natural selection, adaptive radiation, and major geological eras to grasp the concept of deep time.
150
3 sheets
Permian Extinction
250
5 sheets
Cambrian Explosion
540
10.8 sheets
Snowball Earth
650
13 sheets
Origin of Life
3,800
76 sheets
Formation of Earth
4,600
92 sheets
Facilitating the Closure
Human History on this scale:
"300,000 years ÷ 50,000,000 years/sheet = 0.006 sheets. This is roughly 0.6% of a single sheet of toilet paper—essentially just the thickness of the perforated line or a tiny pencil mark at the very end of the roll."
Discussion Prompts:
"If you blink, you miss human history. What does that tell us about the planet we live on?"
"How many 'episodes' of mass extinctions did life survive before we arrived?"
"Does seeing this scale make you feel small or significant? (Most kids feel both: small in time, but significant for surviving the 'lottery' mentioned in the video)."