# Mastery: Reasoning and Problem-Solving

Y1

• Set up using small world play equipment.
There are 7 ducks in the pond. If 2 get out, how many are left?
Write a matching number sentence. If 3 more get in, how many ducks are on the pond? Write a matching number sentence.
If 2 get out, how many are left on the pond? Write a matching number sentence.
• Draw a number track from 1 to 10.
 1 2 3 4 5 6 7 8 9 10

Place your counter on a number. Write it. Now hop along 2. Where do you end up? Write the addition. Repeat.
Place your counter on a number. Write it. Now hop back 2. Where do you end up? Write the subtraction. Repeat

• Write the missing numbers:
7 – 3 = ☐
5 + ☐ = 6
☐ + 2 = 5

Y2

• What number is subtracted from 83 to give 73?
What number is subtracted from 50 to give 29?
What number is subtracted from 48 to give 37?
• Write the missing numbers in the sequences:
76, 56, ☐, ☐
☐, 85, 74, ☐, ☐
☐, ☐, 45, ☐, ☐, 39
• Write the missing numbers:
76 – ☐ = 55
☐ – 11 = 47
• How many times can 21 be subtracted from 100 before you get a number smaller than 21?

In-depth Investigation
Y1: Number Balance
Can you hang weights in the right place to make the equaliser balance? Number Balance from nrich.maths.org.

Y2: Getting the Balance
If you hang two weights on one side of this balance, in how many different ways can you hang three weights on the other side for it to be balanced? Getting the Balance from nrich.maths.org.