Are the following statements about number always true, sometimes true or never true?
How do you know?
Can you find examples or counterexamples for each one?
For the 'sometimes' cards can you explain when they are true? Or rewrite them so that they are always true or never true?
When you add two numbers you

If you add 10 and take away 1,

When you add 10 to a number,

When you subtract one number from another number you can change the order and the answer will be the same 
What about these statements about shapes?
If you put two squares together

3D shapes have more than

When you cut a square in half

Four sided shapes are called squares 
Three sided shapes are called triangles


You could cut out each set of cards from this sheet (word, pdf) and arrange them in this grid.
Alternatively, you could use these interactivities to organise your thinking: