Or search by topic
If you have ten counters numbered $1$ to $10$, how many can you put into pairs that add to $10$?
Can you use them all?
Say how you got your answer.
Now put the counters into pairs to make $12$.
Now put the counters into pairs to make $13$.
Now put the counters into pairs to make $11$.
This problem looks simple to start with, but it has a certain complexity. It is a great opportunity to encourage children to justify their thinking, which they may find quite difficult at first.
All children will need access to ten counters or number cards numbered from $1$ - $10$. Having counters to move around will help free up their thinking and means they can try out lots of ways without the fear of having something committed to paper which might be wrong. Some children may also need some unnumbered counters or Multilink cubes to help them with the calculations.
What goes with this number to make $10$/$11$ etc?
Children could try to find other numbers of which can be made from pairs of the numbers $1$ - $10$. Are there any number which can't be used?
What can they do if they use the numbers from $1$ - $12$ instead of $1$ - $10$?
Some learners may need support with the calculations, so having number lines, blank counters or other equipment available will be useful. This task offers children the chance to practice adding numbers in a meaningful context.
What is the greatest number of squares you can make by overlapping three squares?
Find all the numbers that can be made by adding the dots on two dice.
Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?