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Flat or Solid? is a free printable Kindergarten math worksheet on distinguishing two and three dimensions, aligned to Common Core standard K.G.A.3. It prints 5 questions with an answer key on its own sheet of paper, in 25 versions that each ask different questions, so no two students in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 1 of 25 · the same problems every time you open this link.

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One paper per student

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All 25 sets ask different questions.

Flat or Solid?

K.G.A.3

NameDate

Sort each one into the right box.

1.Sort each one into the right box.

Sort: cube, circle, prism, triangle

FlatSolid
2.Sort each one into the right box.

Sort: cylinder, square, prism, cube

FlatSolid
3.Sort each one into the right box.

Sort: pentagon, prism, circle, square

FlatSolid
4.Sort each one into the right box.

Sort: cone, pentagon, pyramid, hexagon

FlatSolid
5.Sort each one into the right box.

Sort: triangle, cone, circle, pentagon

FlatSolid

LessonPrint · K.G.A.3 · Set 1 · free to copy for classroom use

Answer key — Flat or Solid?

Set 1. Prints on its own sheet.

  1. 1.Flat: circle, triangle; Solid: cube, prism
  2. 2.Flat: square; Solid: cylinder, prism, cube
  3. 3.Flat: pentagon, circle, square; Solid: prism
  4. 4.Flat: pentagon, hexagon; Solid: cone, pyramid
  5. 5.Flat: triangle, circle, pentagon; Solid: cone

Questions about Flat or Solid?

What does the Flat or Solid? worksheet cover?

It practices distinguishing two and three dimensions — 5 questions for Kindergarten, all on Common Core K.G.A.3: Tell flat shapes apart from solid ones. The instruction to students is “Sort each one into the right box”, and the answer key follows on the next sheet.

Which Common Core standard does Flat or Solid? practice?

CCSS.MATH.CONTENT.K.G.A.3 — K.G.A.3, under Geometry for Kindergarten. The published standard reads: “Identify shapes as two-dimensional (lying in a plane, "flat") or three-dimensional ("solid").” The worksheet assesses that standard rather than a paraphrase of it.

What age or grade is this worksheet for?

Flat or Solid? is written for Kindergarten, typically ages 5-6. It is one of the sheets on K.G.A.3, so it suits any student working at that standard — including older students revisiting it and younger ones working ahead.

Does Flat or Solid? come with an answer key?

Yes. All 5 answers are generated from the same problems as the questions, so the key cannot drift out of step with the sheet. It starts on a fresh sheet of paper, after the questions, so it is not handed out with the class by accident.

How many different versions of Flat or Solid? can I print?

25 — one per student, and all 25 ask different questions. Set 1 downloads the whole class as a single PDF. Every version is fixed to its own address, so a sheet printed today holds the same problems when you reopen it next week.

Is Flat or Solid? free to print and photocopy?

Yes. Flat or Solid?, its answer key and its 25 versions are free to print and photocopy for your own class, with no account, no email capture and no subscription at the download step. Please do not resell them or republish them as your own.

Is there a lesson plan to teach K.G.A.3?

Yes — “Flat Shapes and Solid Shapes” is a 30-minute Kindergarten plan for K.G.A.3, timed section by section, with the misconceptions to expect and an exit ticket. Flat or Solid? is the practice that follows it.

More practice for K.G.A.3

Tell flat shapes apart from solid ones.

Teaching this next? Flat Shapes and Solid Shapes is the 30-minute plan for it, with the misconceptions to expect.

All Kindergarten worksheets

Last reviewed 2026-09-05. Aligned to K.G.A.3 of the Common Core State Standards for Mathematics.