Planning and Activities
Day 1 Teaching
Ask children how we could solve 65 – 24. Do we count back in ones? Draw out that we can count back 20, and then subtract 4. Say we use a number fact: 5 – 4. Repeat for 85 – 24. Draw on the landmarked line, and also as an empty number line jotting. Repeat for 85 – 30, 85 – 33, 77 – 33, 96 – 32.
-- Play a card game to subtract two 2-digit numbers and draw accurate empty number lines.
-- Subtract two 2-digit numbers: identify answers that will be less than 50.
Day 2 Teaching
Show 85p as 50p, three 10ps and a 5p coin. A banana is 33p. Move away three 10p coins and count back in 10s. Now we take away 3. What is 5 take away 3? Remove the 5p coin and replace with a 2p coin. Repeat with similar subtractions.
Use the in-depth problem-solving investigation ‘Build it Up’ from NRICH as today’s group activity.
Or, use this activity:
-- Find missing numbers in subtraction calculations.