Recall the facts up to 10, and the teen facts.
Number Framework Stage 4
Group the students in pairs or small groups each with a stack of 10 cubes. Without the others seeing, a student takes some cubes from the stack. They show the other students the remaining cubes and ask the students to say how many cubes were taken.
The problem is made more difficult if cubes are removed from both ends of the stack.
Extension Activity
Take two stacks of 10 cubes, giving 20. Play the same game removing cubes from both stacks, handing the remaining cubes to a partner to work out how many were removed.