Thursday, October 8 — Day 28
The long line. Millions of years ago.
The clock
Same as yesterday. Work 9:30–10:10, break, 10:30–11:10 on the printed sheet with the filled side down, break, 11:30–12:10, break, exam 12:30–1:00. Phones off until 1:30. The sheet is on the desk. Put it away before the exam.
The idea
One line. Oldest at the top, us at the bottom. The number is how many millions of years ago.
| What | Million years ago |
|---|---|
| Big Bang | 13800 |
| Earth forms | 4540 |
| First life | 3700 |
| Cambrian explosion | 540 |
| First fish | 520 |
| First land plants | 470 |
| First dinosaurs | 230 |
| First mammals | 210 |
| Asteroid, dinosaurs gone | 66 |
| First hominids | 7 |
| Homo sapiens | 0.3 |
Fish come just after the Cambrian. Mammals come just after dinosaurs. Humans are the last mark, almost now.
The exam takes an answer within about 10 percent. 520 and 500 are the same idea. 0.3 can be answered as 0.
A few questions are yesterday’s multiply, so the last addition does not disappear.
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