Compose and Subtract Tens

Overview

Students add and subtract within 100 using place value strategies with hands-on models, quick movement, and a short chant. The lesson emphasizes adding tens and ones (and composing a ten when needed) and relates the strategy to a written method.

Learning intentions

• Students will be able to add a two-digit number and a one-digit number within 100 using tens and ones models.
• Students will be able to subtract a multiple of 10 (10–90) from a two-digit multiple of 10 within 100 using place value.
• Students will explain their strategy by talking about tens and ones (and composing a ten when it’s necessary).
• Students will connect what they model to a written number sentence.

Success criteria

• I can show tens and ones with base-ten blocks/drawings to solve an addition or subtraction problem within 100.
• I can write the number sentence that matches my model.
• I can tell whether I added/subtracted tens, ones, or both.
• I can explain when I need to “make a ten” (compose a ten) during addition.

Curriculum links

• Number and Operations in Base Ten — add within 100 using concrete models, drawings, place value, and composing a ten.
• Number and Operations in Base Ten — subtract multiples of 10 from multiples of 10 using place value strategies.
• Number and Operations in Base Ten — relate strategies to written methods and explain reasoning.

Lesson structure (15 minutes)

1. 0–3 min · Whole-group routine + chant

• Teacher draws 34 + 5 on the board and says the chant: “Tens stay, ones change—if ones reach ten, we make it!”
• Students show with fingers: number of tens (3) and ones (4) for 34, then quickly show “5 more ones” with a second finger motion.

2. 3–8 min · Direct teach with hands-on modeling (I do → we do)

• Teacher models 34 + 5 using base-ten blocks (or place value cards): build 34 with 3 tens rods and 4 ones cubes, then add 5 ones cubes.
• Teacher points out composition: when ones reach 10, exchange 10 ones for 1 ten, then count tens and ones to get the sum; students answer together and explain in one sentence.
• Teacher records the written method: “34 + 5 = 39” and asks, “How do you know without starting over at 1?”

3. 8–11 min · Movement check: “Tens Jump” (we do → quick pairs)

• Teacher sets up the room with two areas labeled “Tens” and “Ones” and places problem cards on the floor.
• Teacher calls: “If the next move is adding 10, run to the Tens side! If it’s subtracting ones, run to the Ones side!”
• Students respond to 2 quick prompts (teacher calls each prompt, then students move to the correct side and say the place value part of the strategy).

4. 11–14 min · Centers (independent or teacher-led), game-style

• Students rotate through two mini-center options (about 1 minute each prompt, teacher chooses grouping based on class flow). Keep directions consistent and short.
• Center A (teacher-led): “Blocks to Number Sentences” Teacher displays one problem: 40 − 10 and one: 60 − 30 (choose based on readiness). Students build with tens rods only, then write the number sentence and explain: “I subtracted tens.”
• Center B (independent): “Make a Ten Dash” Students use digit cards or ten-frame/part-part-whole cards to solve 26 + 7 or another teacher-prepared match. They must show the model first, then write the sum. A student can only “dash” (check a box) after they explain: “I composed a ten because my ones added to 10 or more.”

5. 14–15 min · Exit ticket (quick, written)

• Students complete two items on a half-sheet:
• 1. Draw or show tens/ones: 37 + 8 = ____
• 2. Write and explain with place value: 80 − 20 = ____

Resources

• Base-ten blocks (tens rods and ones cubes) for teacher and students
• Place value mats or quick ten-frames
• Problem cards for movement (“adding tens,” “subtracting tens,” “ones change”)
• Center materials: digit cards (tens/ones), ten-frame cards, and dry-erase boards
• Printed exit tickets
• Timer for centers (simple visible countdown)
• Optional: class chant cue card with “Tens stay, ones change…”

Assessment

• Teacher listens during the whole-group explanation: Can students name tens vs ones and mention composing a ten when needed?
• During centers, use a quick observation checklist: model shown → number sentence written → explanation includes tens/ones.
• Exit ticket checks both addition with composing a ten and subtraction of a multiple of 10.

Differentiation

• Support:
• Provide sentence starters at centers: “I added tens…” “I added ones…” “I made a ten by…”
• Offer partially completed written frames: “__ + __ = __” and a place value diagram template.
• For students needing extra scaffolding, use only problems where composing a ten clearly happens (e.g., 24 + 6, 50 − 20).
• Extension:
• Add a third center challenge card: 45 + 6 or 90 − 10 and require a two-sentence explanation (model + reasoning).
• EAL/SEN considerations:
• Keep language consistent with a class routine (“tens,” “ones,” “make a ten,” “subtract tens”).
• Allow drawing or blocks instead of long writing; count accuracy is the priority.
• Small-group option:
• If several students struggle in Center A, keep them there for one extra problem while Center B runs with the rest.