Lesson 2 of 19
A move each way
Show on a big screenA cold room reads −7 °C (degrees Celsius). It warms by 3 degrees. What does it read now?
Step 1 of 3
- Start at −7.
- Add 3. Walk 3 right.
- 7 is bigger than 3. Land on −4.
The room reads −4 °C now. The 3 steps right undo 3 of the 7 steps left. So 4 steps left remain.
A move's size is its number of steps. Its side is left or right.
Rule: a move each way? Take the smaller size from the bigger. Keep the bigger move's side.
| Sum | Sizes | Bigger move | Lands on |
|---|---|---|---|
| (−5) + 2 | 5 and 2 | left | −3 |
| 5 + (−8) | 5 and 8 | left | −3 |
| (−2) + 9 | 2 and 9 | right | 7 |
| 6 + (−6) | 6 and 6 | neither | 0 |
Two equal moves cancel: one undoes the other. They end at 0, which is neither side.
Tap the side where the answer ends. Then watch the walk.
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Try the lab to finish this lesson.