LESSON PLAN

Change in Quantity to 20

Apothem Team

Grade 1 · Number

LESSON AT A GLANCE

Warm-up

5 min

Explore

15 min

Consolidate

10 min

Practice

12 min

Exit ticket

3 min

Warm-up

I have 10 cubes on my mat. Watch what I do. Add 4 cubes. What happened? How many now? How do you know? Remove 3. What happened now? How many? Build comfort with describing change before asking students to write equations.

Explore

Build-and-change challenge: students draw a start card (e.g., 12) and an end card (e.g., 17). They build the start with cubes, change it to reach the end, and describe what they did. Record as an equation. Next round: draw an end and change card and find the start.

Consolidate

Practice

Students complete 4 change problems, one of each structure, writing the equation and drawing the change. Exit ticket: teacher poses ?+6=15. Students write the equation and solve.

Exit ticket

Students complete 4 change problems, one of each structure, writing the equation and drawing the change. Exit ticket: teacher poses ?+6=15. Students write the equation and solve.

TIP Insist on complete verbal descriptions: I started with ___, I added/removed ___, now I have ___. This sentence stem, repeated consistently, builds the language structure that maps directly onto equation syntax.

WORKED EXAMPLES

Change-unknown problem: I had 7 apples. After getting some more I have 12. How many did I get?

I need to get from 7 to 12. Count on: 7 ... 8, 9, 10, 11, 12: that is 5 steps, so I got 5 apples. Or: I know 7+5=12. Record as 7+?=12, answer 5.

A student writes 15-8 correctly but cannot explain their strategy. How do you check understanding?

Ask: How did you get 7? If they say I counted back from 15 or I know 8+7=15, they understand. If they cannot explain, use a number line to develop the reasoning: start at 15, jump back 8 steps, where do you land?

MATERIALS

•Linking cubes

•Story mats

•Change recording sheets

•Number lines 0-20

•Student whiteboards

WATCH FOR

!Students may confuse adding (joining) with multiplying (grouping). Keep all change contexts clearly about joining or separating single quantities.

!Students may write equations in reversed order (13=8+5) and think it is wrong. Reinforce that = means balanced with. Both orders are correct.