– Take turns to subtract a number between 1 and 9 inclusive from the number displayed. – The person who avoids making the calculator display zero is the winner.
For the Teacher:
– Play a game with the whole class discussing & demonstrating number strategies. – Model a few games in front of the class with one calculator for you & one for each pair of students – computer calculator on IWB or data projector – draw the calculator display on the whiteboard. – You are not to change the numbers in any other column. Only the column stated’. – ‘Don’t forget to press the subtraction button on the calculator!!!’ – You must do the algorithm mentally and tell your partner the solution before you press the ‘equals’ button. – press ‘equals’ to confirm – reflect on the strategy you used if you arrived at an incorrect answer. – Discuss the developing stages of computations – use of fingers – use of strategies – automaticity – i.e. ‘See it, Say it’ – Fingers work for starters but are a slow inefficient strategy. – Why might it be important to achieve ‘ automaticity’? – Where are you at as a learner? – I know that under stress I revert back to what I’m sure of. Discuss. – Walk the room checking the tasks are being done – stand a short while behind the pair that you ‘suspect’ – you know the ones I mean 🙂 – Ask – ‘What numeral is in Tens of Thousands, Thousands, Hundreds, Tens, Units column? – Ensure the students are verbalizing their thinking. – Zero is a numeral – the letter O is a letter – insist students use mathematical vocabulary. – What is the difference between a numeral and a number? – Say ‘Gee Gee’ at the end of the game. It stands for ‘Good Game’.
Developing Number Strategies:
Play the game over a week with different skill/strategy focuses:
– only allowed to subtract 5 – only allowed to subtract 6 (-5 – 1 more) – only allowed to subtract 7 (-5 – 2 more) – only allowed to subtract 8 (-10 + 2 more) – only allowed to subtract 9 (-10 + 1 more) – Color in a hundreds grid to find the patterns. – Discuss ‘Jumps to decades’. – How can the ‘Facts to Ten’ help arrive at answers more quickly? 9+1, 8+2, 7+3, 6+4, 5=5, 4+6, 3+7, 2+8, 1+9 – What strategy works for you?
Something to reveal and explore after playing the game for a while 🙂
– Here is a sequence of numbers that will help you win the game every time if you start first.