Teaching and Group Activities for Understanding
Day 1 Teaching
Discuss contexts in which we use negative numbers: temperature, depth, debts, etc. Launch the ITP Number Line. Choose –20 to 20 range. Click so that the numbers are not displayed on the tags. Children identify numbers. Mark –2 and –8. What numbers are in-between? Repeat with +3 and –4. Ask children to write a number between –15 and 15 on a whiteboard. Gradually create a human number line, with children negotiating their position in the line.
-- Practise ordering number cards –10 to 10.
-- Order sets of three –15 to 15 number cards using < and >. Play a team game.
Day 2 Teaching
Show a horizontal counting stick. Identify the end as –10. Count from this to +10. Then start at –40 and count in steps of 5. Start at –100 and count in 10s. Start at –200 and count in 25s. Repeat, counting back and forth across 0 in different size steps. Discuss situations in ‘real life’ where these sorts of subtractions are possible, e.g. falls in temperature, descending below sea level, or being overdrawn at the bank.
Use the in-depth problem-solving investigation ‘First Connect Three’ from NRICH as today’s group activity.
Or, use these activities:
-- Play a game to practise counting back through zero to -20 and beyond.
-- Repeatedly subtract from the first number in a given pair to exactly reach the second.