1.MD.1: Order and Compare Lengths Indirectly
Also written as 1.MD.A.1 and CCSS.MATH.CONTENT.1.MD.A.1 · Cluster: Measure lengths indirectly and by iterating length units.
The Official Wording
Order three objects by length; compare the lengths of two objects indirectly by using a third object.
Common Core State Standards, Grade 1, Measurement & Data · Read it at the source · Checked October 14, 2026
What 1.MD.1 Means in Plain English
First graders line up three crayons at one edge and read them from shortest to longest. Then they compare two things that cannot sit side by side: a strip of yarn cut to the desk’s length, carried to the rug, shows which of the two is longer.
The new idea is reasoning through the go-between: the rug is longer than the yarn, the yarn matches the desk, so the rug is longer than the desk. Next, units replace the yarn (1.MD.2), and in 2nd grade students find how much longer in inches (2.MD.4).
1.MD.1 I Can Statements
- I can put three objects in order from shortest to longest.
- I can use a string to compare two things that cannot move.
- I can explain which is longer by comparing each to the string.
1.MD.1 Worked Example
Two pieces of classroom furniture that will never sit side by side, compared with one strip of yarn.
The reading rug is on one side of the room and the teacher’s desk is on the other. Neither one can be moved. Which is longer?
- The rug and the desk cannot be lined up, so we need something that can travel between them. A long piece of yarn will do.yarn, scissors, the rug, the desk
- Hold one end of the yarn at one end of the desk, stretch it along the desk’s long edge, and cut it right at the other end.a piece of yarn exactly as long as the desk
- Carry the yarn to the rug. Put its end exactly at the rug’s edge and stretch it straight along the rug.yarn end lined up with the edge of the rug
- Look at the far end. The rug keeps going after the yarn runs out.the rug sticks out past the yarn
- Put the two facts together: the rug is longer than the yarn, and the yarn is as long as the desk.rug longer than yarn, yarn same as desk, so rug longer than desk
Check it: Cut a second piece of yarn to the rug’s length and lay it along the desk. It hangs past the end of the desk, which tells the same story from the other side.
Common Mistakes with 1.MD.1
A crooked or slack string
The yarn curves across the rug instead of running straight, so it reaches less far than it should
Try this: Pull the yarn tight with a partner holding each end, and check that it runs straight along the edge before anyone reads it.
Stopping halfway through the reasoning
“The rug is longer than the yarn.” and no answer about the desk
Try this: Have the child point to each object while saying the chain aloud: rug beats yarn, yarn matches desk, so rug beats desk.
Ordering three by checking only two
The crayon is shorter than the pencil, so the marker goes last, though the marker was never checked
Try this: Line up all three at the same starting edge so every far end shows at once, then read them from shortest to longest.
Where 1.MD.1 Fits
Practice 1.MD.1
Quick Check
- A pencil is shorter than a marker. The marker is shorter than a ruler. Which is longest, and which is shortest?
- Ava cuts a string as long as the bookshelf. The string does not reach the end of the window. Which is longer, the bookshelf or the window?
- Why line up three crayons at the same edge before putting them in order?