Kindergarten · lesson 4 of 4

Combine Pieces Without Gaps or Overlap

Use the supplied description of a shape split into pieces.

About 15 minutes, plus any extended practice

Download the grade pack

Supplied materials

  • Paper and a pencil; drawing and spoken explanations are welcome. An adult may read directions and options aloud.
  • Supplied worked-case record: A rectangle is cut straight down the middle into two smaller rectangles.
  • All quantities and shape descriptions are supplied in the worked example and questions; no purchase or personal information is needed.

Learn the idea

A larger shape can be made from smaller pieces. The pieces must fit with their edges touching and their inside regions separate. A gap leaves some of the whole missing; an overlap counts part of the space twice. Matching pieces can be moved or turned to fit.

Use the supplied description of a shape split into pieces. Imagine or draw the pieces in their original positions. Decide which completed whole they rebuild when matching edges meet.

Trace the target outline before joining pieces. A correct flat composition has no inside gaps or overlaps. Draw the original whole and indicate each separate piece with a different pattern.

  1. Draw the original whole and indicate each separate piece with a different pattern.
  2. Follow the worked example. Point to each number or shape feature and say what it tells you.
  3. Use the supplied description of a shape split into pieces.
  4. Try the question and then the three practice questions. Check your answers and explain any change you make.
Worked example

See the method in action

A rectangle is cut straight down the middle into two smaller rectangles. Joining the cut edges rebuilds the original rectangle. Stacking one piece on top of the other does not rebuild its flat area because the pieces overlap rather than cover adjacent regions. Trace the target outline before joining pieces. A correct flat composition has no inside gaps or overlaps. Draw the original whole and indicate each separate piece with a different pattern.

Your turn

Check your reasoning

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Helpful tips
  • Trace the target outline before joining pieces.
  • A correct flat composition has no inside gaps or overlaps.
A square is split along a diagonal into two triangles. Joining the cut edges rebuilds what?

Feedback appears here after you check. This is practice, not a graded school assessment.

See the answer and explanation

Square

The two original triangular pieces cover the original square.

Take it further

Sketch a rectangle split into two triangles. Expected: matching diagonal edges can rebuild the rectangle.

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More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

More practice: try new cases
1. A circle is cut into two equal half-circles. Joining their straight cut edges rebuilds what?
Need a hint?
  • Trace the target outline before joining pieces.
  • A correct flat composition has no inside gaps or overlaps.
2. A rectangle is cut into two smaller rectangles. Joining the cut edges rebuilds what?
Need a hint?
  • Trace the target outline before joining pieces.
  • A correct flat composition has no inside gaps or overlaps.
3. Two pieces cover one region twice. What is the problem?
Need a hint?
  • Trace the target outline before joining pieces.
  • A correct flat composition has no inside gaps or overlaps.

Your choices are temporary. Feedback appears after you check all the answers.

Nothing here is saved to an account or sent to a teacher. Keep your own notes or download them before leaving. The score describes these questions; it does not certify subject mastery.

Check the subject sources

These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.