You Don't Need the Number

Using Materials

Problem: “Jean has 45 lollies. She eats 4 of them. Now her grandmother gives her 4 more lollies.How many lollies does Jean have now?”

Write 45 – 4 + 4 on the board. Get the students to model the story with counters. Write the answer on the board.

Examples: Word stories and recording for: 43 + 5 – 5

26 – 6 + 6
52 – 3 + 3
14 + 8 – 14
34 + 3 – 34 ...

Using Imaging

Problem: “Gavin has 56 apples. He eats 6 of them. He buys 6 more apples. How many apples does Gavin have now?”

Shield 56 objects from the students. Show them the 6 Gavin eats. “How many are left?” Add 6 more to the shielded apples. Ask how many there are now.

Examples: Word stories and recording for: 25 + 4 – 4

58 – 7 + 7
28 + 15 – 28
23 – 9 + 9 ...

Using Number Properties

Examples: Word stories for: 345 + 907 – 907

234 + 69 – 234
689 – 341 + 341
345 + 89 – 345 ...

Understanding Number Properties:

Find the answer to 500 – ? + ?, where the number is the same in both boxes. Would it matter what number went in the boxes? (Answer: No. Whatever number is in the boxes, the answer is always 500.)