Number talks: a 10-minute warm-up that builds mental math

1. Write one problem horizontally, such as 18 × 5. Writing it this way discourages the stacked paper method.
2. Give quiet thinking time. Students show a thumb on their chest when they have an answer, and an extra finger for each additional way they find. This keeps fast thinkers busy without pressure on anyone else.
3. Collect answers without saying which is right. Write them all down.
4. Ask a few students to explain how they got their answer. Record each strategy exactly as they say it.

For 18 × 5, you might hear:
"10 × 5 is 50 and 8 × 5 is 40, so 50 + 40 = 90."
"18 × 10 is 180, and half of that is 90."
"20 × 5 is 100, minus 2 × 5, which is 10, gives 90."

5. Ask: "Which strategy would you use for 18 × 50?" (Using the second idea: 18 × 100 = 1,800, half is 900.)

Good problems to start with: 25 × 12 (think 25 × 4 = 100, so 25 × 12 = 300), 99 + 47, or 63 − 28.

Keep the tone curious. A wrong answer is welcome, because talking it through is where the learning happens.

What to change next time: for students who need support, start with addition and subtraction within 100 and give a number line. For students who are ready, try problems like 3.5 × 4 or 1/2 of 86.