3rd grade | old DOT

Addition & Subtraction in the 100s and 1,000s

Working with word problems
- We recommend these addition worksheets and these subtraction worksheets
- Encourage students to write equations from the word problems, in both long addition/subtraction form and horizontally.
- For some problems, solve with long addition/subtraction form and for others, use these virtual base ten blocks.

Repeated Addition

“Repeated Addition” is the precursor to multiplication and is exactly what it sounds like.

Students must create addition equations from word problems (you can make these up!)
- e.g. Peter buys 2 apples on every week day, how many does he have at the end of the week? → 2+2+2+2+2=10
- Encourage students to physically add items multiple times (small toys like legos work well!) and make sure they deliberately count the total number of items at the end, as opposed to just doing the math - this helps them avoid mistakes
- Use this worksheet as inspiration for your word problems
Use “arrays” to model repeated addition

Kids should be able to identify the rows and columns and conclude that the sum is always the same (e.g.5+5+5=3+3+3+3+3)

When using arrays, differentiating between rows and columns using different colors and shapes can be helpful! Make rows each a different color so they understand that rows go side to side, then switch and do the same with columns.
Students tend to get confused about how many rows (or columns) there are versus how many items are in a row. Go through this slowly, and maybe do a problem on your own that they can watch.
These worksheets are great practice

Tip: Previously, in order to learn place value, students are taught to think of things in groups of tens and ones (e.g. 63 is six 10s and three 1s). Repeated addition teaches students that any number, not just powers of ten, can be a unit. Making equal groups of “four apples each” establishes the unit “four apples” (or just four) that can then be counted: 1 four, 2 fours, 3 fours, etc.

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