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Ordering Objects by Length

A 40-minute Grade 1 lesson on ordering three objects by length and on comparing two things that cannot be moved next to each other, using a third object as a go-between.

Ordering Objects by Length is a free 40-minute Grade 1 maths lesson plan for Common Core standard 1.MD.A.1 — put objects in order from shortest to longest. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.

Grade:
Grade 1
Length:
40 minutes
Standard:
1.MD.A.1

Grade 1 · Measurement & Data

1.MD.A.1

Order three objects by length; compare the lengths of two objects indirectly by using a third object.

Objective

Students will be able to order three objects by length and compare two objects indirectly using a third.

Students are successful when they can

  • Orders three objects shortest to longest using two comparisons.
  • Uses a strip of paper to compare two things that cannot be placed side by side.
  • Explains that if A is longer than B and B is longer than C, then A is longer than C.

What you need

  • Sets of three strips or straws of similar lengths
  • String or paper strips for indirect comparison
  • Two objects fixed in place — a door width and a shelf, for example
  • The printable practice sheet linked at the end of this plan

The lesson

Warm-up — two at a time

5 min
  1. Compare two strips by lining them up at one end. Say both sentences: this is longer, that is shorter.
  2. Ask how many comparisons would be needed for three strips. Take the guesses and move on.

Teach — ordering and the go-between

12 min
  1. Take three strips. Compare A with B, then B with C. Order them without ever comparing A with C directly.
  2. Ask whether you can be sure A is longer than C. Push for the reasoning, then check by comparing them.
  3. Now the harder problem: is the door wider than the bookshelf? They cannot be moved together.
  4. Cut a paper strip the width of the door. Carry it to the shelf. The strip is longer, so the door is wider.
  5. Name what the strip did: it carried the length across the room. Nothing was measured and the question was answered.
“If you cannot put two things next to each other, put something next to each of them instead. The go-between remembers the length for you.”

Guided practice — order and carry

11 min
  1. Pairs order three strips shortest to longest and record the order.
  2. Then they compare two fixed objects in the room using a paper strip and report which is longer.
  3. Ask each pair how many direct comparisons they actually made.

Independent practice

9 min
  1. Students complete an ordering lengths page.
  2. On paper the objects are drawn from different baselines. Watch whether pupils account for the starting points before ordering.

Close

3 min
  1. Ask whether your desk is longer than the classroom door is wide, and how they would find out.
  2. The method matters more than the answer here.

What goes wrong, and why

Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.

Orders three strips by comparing each with the first only.

Why: One comparison per object seems like enough work, and the relationship between the second and third has not been recognised as a separate question.

Fix: Give three strips where the two shorter ones are nearly identical. Comparing both against the longest cannot separate them, and the missing comparison declares itself.

Says an indirect comparison cannot be trusted without seeing both objects together.

Why: The go-between introduces a step the pupil cannot see the whole of at once, and scepticism about that is reasonable rather than confused.

Fix: Do one where the objects can be brought together afterwards to check. Once the method has been confirmed twice, it gets trusted on its own.

Uses a strip longer than both objects and concludes nothing.

Why: The strip has been treated as a ruler rather than as a copy of one specific length.

Fix: Cut the strip to exactly match the first object. It is a copy of that length, not a measuring tool, and cutting it makes that concrete.

If they are not there yet

  • Order three objects with large differences before moving to near-equal ones.
  • Line every comparison up against a table edge so the common starting point is not a separate thing to remember.

If they finish early

  • Order five objects and count the smallest number of comparisons needed.
  • Compare two objects using a go-between that is shorter than both, by marking it twice.
  • Measure both objects in cubes and check the ordering agrees.

Exit ticket

Ribbon A is longer than ribbon B. Ribbon B is longer than ribbon C. Which is longest? How do you know?

What to look for: A, with reasoning that chains the two facts. 'I would have to see them' means the indirect argument has not been accepted yet — worth another go-between task, not a correction.

Printable practice for 1.MD.A.1

Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.

Questions about Ordering Objects by Length

How long does the Ordering Objects by Length lesson take?

40 minutes, split across 5 timed sections: warm-up 5 min, teach 12 min, guided practice 11 min, independent practice 9 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.

Which standard does Ordering Objects by Length teach?

CCSS.MATH.CONTENT.1.MD.A.1 — 1.MD.A.1, Measurement & Data for Grade 1: “Order three objects by length; compare the lengths of two objects indirectly by using a third object.” In plain terms, put objects in order from shortest to longest.

What do I need to teach this lesson?

Sets of three strips or straws of similar lengths, string or paper strips for indirect comparison, two objects fixed in place — a door width and a shelf, for example and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.

What mistakes should I expect in this lesson?

Three, each a reasoning error rather than carelessness: orders three strips by comparing each with the first only; says an indirect comparison cannot be trusted without seeing both objects together and uses a strip longer than both objects and concludes nothing. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.

How do I know whether the lesson worked?

The exit ticket asks: “Ribbon A is longer than ribbon B. Ribbon B is longer than ribbon C. Which is longest? How do you know?.” A, with reasoning that chains the two facts. 'I would have to see them' means the indirect argument has not been accepted yet — worth another go-between task, not a correction. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.

Is there a worksheet to go with Ordering Objects by Length?

Yes — 2 printable 1.MD.A.1 worksheets, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.

Is Ordering Objects by Length free to use?

Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 5 September 2026. Please do not resell it or republish it as your own.

Last reviewed 2026-09-05. Aligned to 1.MD.A.1 of the Common Core State Standards for mathematics.