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Grade 2 · Mathematics · 20 minutes

Partition a whole

Draw two identical rectangles. Equal shares can have different shapes.

Mr. S Teaches · Starter mini-lesson · elem-2-partition-a-whole

Learning objective

Explain and practice partition a whole using the activity and evidence, then show the reasoning behind an answer.

Gather your materials

  • Paper and pencil
  • Counters, blocks or paper pieces
  • A ruler, clock model or grid when named in the steps

Use the items named in the teaching steps; paper models or adult-prepared photographs can replace physical equipment.

Common Core skill focus

2.G.A.3

Name equal shares and recognize that equal shares can have different shapes.

Read the official standard ↗

Code and grade verified 2026-11-03. This mini-lesson addresses a selected skill, not the entire standard.

Teach it step by step

  1. Draw two identical rectangles.
  2. Divide one into four equal vertical strips.
  3. Divide the other into a two-by-two grid.
  4. Compare the shares and verify that four shares rebuild each whole.

Watch, notice, discuss

Video choices for this lesson

2 choices

Preview a video, then choose what fits your learners. “Show to class” opens a larger view; use the player’s play and full-screen controls when you’re ready.

Teacher preview needed. Check the language, level and length before showing. YouTube may show ads or related videos.

After watching

Show halves, thirds or fourths of equal-sized wholes. Can equal shares look different?

An external player loads only after you choose Preview or Show to class. Playback connects to YouTube. Videos belong to their creators; availability and embedding can change.

Make the thinking visible

Example to work through together

Each strip and each small grid rectangle is one fourth of its whole, although the shapes differ.

Try the starter activity

Divide two identical rectangles into fourths in two ways.

Student practice

Make thirds in two identical rectangles in different ways and explain why the shares must be equal within each whole.

Quick check for understanding

Must all fourths look the same across different partitions?

Sample answer and teacher guidance

Sample answer: No; they must each be an equal share of their whole.

Listen or look for: Each whole has three equal-area parts. Shares can have different shapes across the two partitions.

Invite the learner to explain, demonstrate, draw or dictate their reasoning. Revisit a teaching step when the explanation is unclear.

Make it work for your learner

A little more support

Use paper folding or prepared equal partitions.

An additional challenge

Design a misleading partition into four unequal pieces and explain why they are not fourths.