1. Directed numbers
[ N1.3 Support Starter]
How many graduations apart are each of these pairs of numbers?
a) 4 and 2 b) 6 and 1 c) 3 and 0 d) 5 and 3
Jot down the calculations that would give the answers to (a) - (d).
Use what you noticed above to help you calculate the
answers to these:
e) 6 – 2 f) ̄ 1 – 2 g) 2 – 0 h) 2 – ̄ 2
i) ̄ 3 – ̄ 6 j) 0 – ̄ 2 k) 6 – ̄ 2 l) 3 – ̄ 0
Preamble
A small investigation to build up pupils’ confidence in handling negative numbers. The approach of looking at subtraction in turns of jumps in graduations only applies when a smaller number is subtracted from a larger one – depending on circumstances this should be mentioned to pupils.
Possible content
Subtracting and negative numbers using a number line.
Resources
None.
Solution/Notes
a) 2 ( = 4 – 2) b) 5 ( = 6 – 1) c) 3 ( = 3 – 0)
d) 2 ( = 5 – 3) e) 4 f) -3
g) 2 h) 4 (stress graduations) i) 3
j) 2 k) 8 l) 3
Hint: think
graduations!
Original Material © Cambridge University Press 2010
Original Material © Cambridge University Press 2010