Positive and negative number cards
Positive and negative number cards from 1 to 20 (at least one for each child)
I created these number cards whilst teaching Years 1 and 2 to encourage the children’s understanding of 1 more/less, 2 more/less, 10 more/less etc. This concept is a renowned problem area and I hoped my card idea might help. Since teaching years 5 and 6, I have extended the +/- cards to include numbers from 1 to 20 to encourage quick and efficient mental addition and subtraction strategies, an area that the children need to practice frequently. I wanted to do something a little different to really engage them.
Is this a problem for my children?
What I did: KS1: During the starter or in small group work, the children pick a +/- number card at random and, using a number line or 100 square, count on and back from a given number.
How could I support my lower attainers so that they could take part in this with the whole class?
KS2: During the starter, each child picks one +/- number card from a bag and keeps the number to themselves. Using dice, a two or three digit number is generated and written on the board. Then going round the class room, each child has to call out their +/- number and everyone is given 5 seconds to calculate the answer as quickly as possible, before the next child calls out their number. For example, if the original number is 124 and the first card called is +10, the number becomes 134, if the second number is -7, the number is now 127, and so on. By the time all children have called out their +/- numbers, the original number on the board may have changed and returned to its original several times. At the end everyone should have the same answer. The speed at which this activity is carried out is optional, obviously, the main objective is to encourage quick mental strategies, e.g. when subtracting 9, minus 10, then add 1, partitioning a number to make a multiple of ten and then adding/subtracting the rest, doubling and adjusting etc. With practice the children can become quite fast and adept at using a variety of strategies.
‘How could I extend this activity?’
The children’s ability to add and subtract at speed improved greatly over time. Those children who tended to use their fingers to calculate small numbers soon began to use quick mental strategies when calculating. It also improved listening skills. It is a simple but really effective resource!