Number Sentences

On the addition and subtraction mat, you can see these facts:

Circle + Square = Triangle
Square + Circle = Triangle
Triangle – Circle = Square
Triangle – Square = Circle

Put 50 counters in the triangle. If you put 30 counters in the circle and 20 counters in the square, you can write these four addition and subtraction number sentences:

30 + 20 = 50
20 + 30 = 50
50 – 30 = 20
50 – 20 = 30

Change the number of counters in the circle and the square 10 times. In your Lesson Notes, write the number sentences for each change. You will have 40 number sentences in total.

What if you were to change the number of counters in the triangle? In your Lesson Notes, write two or three sentences to explain what would happen to the counters in the circle and the square.