LESSON PLAN

Addition and Subtraction of Whole Numbers to 1,000,000

Apothem Team

Grade 5 · Computational Fluency

LESSON AT A GLANCE

Warm-up

5 min

Explore

15 min

Consolidate

10 min

Practice

12 min

Exit ticket

3 min

Warm-up

Quick mental math using known facts: 7+8=15, so 70+80=? (150). 700+800=? (1,500). 7,000+8,000=? (15,000). 70,000+80,000=? (150,000). Pattern: the sum digit is always 15, with an increasing number of zeros. This is the annex-zeros strategy applied as a pattern.

Explore

Community fundraising challenge: three towns raised funds for a shared project. Town A: $156,234. Town B:$ 289,701. Town C: $94,850. Total raised? Goal:$ 600,000. How far from the goal? Students solve using two strategies each, show an estimate first.

Consolidate

Practice

Students solve 6 six-digit computation problems with estimates and strategies shown. Exit ticket: use annex zeros to solve 80,000 + 70,000 mentally.

Exit ticket

Students solve 6 six-digit computation problems with estimates and strategies shown. Exit ticket: use annex zeros to solve 80,000 + 70,000 mentally.

TIP The annex-zeros strategy is a mental math superpower for large numbers. Teach it explicitly and practice it daily as a warm-up routine.

WORKED EXAMPLES

Solve 400,000 + 300,000 + 50,000 using the annex-zeros strategy.

4+3=7, so 400,000+300,000=700,000. Then 700,000+50,000: 7+0.5=7.5... better to think: 700,000+50,000=750,000 directly.

Estimate then compute: 523,847 - 198,302.

Estimate: 520,000 - 200,000 = 320,000. Compute: 523,847 - 198,302 = 325,545. Close to estimate.

MATERIALS

•Open number lines

•Place value mats

•Number talk display

•Estimation recording sheets

WATCH FOR

!Students may apply annex zeros to cases where the digits don't form a clean fact (e.g., 37,000 + 48,000). Here: 37+48=85, so 37,000+48,000=85,000. The strategy still works, it just requires computing 37+48 first.

!Students may forget to account for regrouping when using decomposition strategies. Estimation provides the check.