M3.1.2 For the adult
Calculating with negative numbers
It is −3 °C at night and 5 °C at noon. How many degrees did it rise?
What this chapter teaches
Adding and taking away are hops on a number line. Two numbers with the same sign multiply to a positive number, and with different signs to a negative one. A pattern that carries on past zero shows why.
Three questions to ask
There is no one right wording. Listen for the idea.
- How far is it from −3 °C up to 5 °C?
- How can you show −4 + 7 as hops on a number line?
- Why is −3 × −4 equal to 12 and not −12?
After the chapter, the learner can
- Find the rise in temperature from −3 °C to 5 °C
- Work out −4 + 7 and 2 − 6 on a number line
- Multiply and divide with negatives, like −3 × −4
What they copy into their notebook
Hop right to add a positive number and left to take one away. Adding a negative moves you left. Same signs multiply to a positive answer. Different signs give a negative answer. Dividing follows the same rule.