Grade: 3, Topic(s): addition/subtraction

## Purpose

To add 19 to any number using mental computation.

None

Tell children to add 19 to each number you say. If children do not suggest it, you may want to offer the mental addition strategy of adding 20 and then subtracting 1. When children are successful with numbers less then 100, progress to three-digit numbers.

Optional: You may choose to record the numbers in a table with the headings *N* and *N* + 19.

Part 1 has children starting at 0, which will allow focus to be given to the +19 strategy of adding 10, adding 10, and subtracting 1. In Part 2, children use what they know to add 19 in a chain, starting at 25. The extension starts at a larger number.

Let’s start at 0 and add 19. Then we’ll add 19 again to *that *result – and keep going until we reach at least 200.

- 0, 19, 38, 57, 76, 95, 114,133,152,171,190, 209

*If children need more practice or are enjoying their mastery, repeat. If children are ready to move on, go to Part 2.*

Let’s start at 25 and add 19. Then we’ll add 19 again to *that *result – and keep going until we reach at least 200.

- 25, 44, 63, 82, 101, 120, 139, 158, 177, 196, 215, 234

*If children need more practice, repeat. Or, when children seem excited for a new challenge, move to the extension.*

Let’s start at 99 and add 19. Then we’ll add 19 again to *that *result – and keep going until we reach at least 300.

- 99, 118, 137, 156, 175, 194, 213, 232, 251, 270, 289, 308

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