Making Ten

My kiddos know their doubles pretty well.
However, I have noticed that when we're trying to make our friendly numbers (numbers that end in zero) they take a while to figure out what each number needs.

We played a VERY basic game to practice making tens.

I gave cups with 10 cubes to each pair of students.
One student grabbed a few cubes, the other student had to guess what was left, then count to be sure.

Start off with ten in a cup.

Then Aubrey pulls out four.

Then Aakash guesses that there are six left.

Then I play a game where I just bounce a ball to a student and give them a number, like 32. Then they have to tell me 32 needs 8 to be 40.