Ordering three things from shortest to longest
In 1st grade, children learn to order three objects from shortest to longest and to compare two lengths by using a third object.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 1st grade practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Which object is usually the longest?
- A book
- A bus
- A shoe
Why this matters
Lining things up and comparing them is your child's first real step into measuring, and comparing two things with a third, like a piece of string, is the logic behind every ruler, tape measure, and measuring cup they will use. Next come units like paper clips, then inches and centimeters in 2nd grade. The reasoning that if A is longer than B and B is longer than C, then A is longer than C, returns again and again.
Where kids can get stuck
- Comparing lengths without lining up the ends, so a shorter pencil that sticks out further looks longer.
- Placing the third object in the wrong spot, putting the middle-length item at one end of the row.
- Ignoring what the string shows and insisting one item is longer because it looks bigger or thicker.
How you can help
- Line up three spoons, crayons, or shoes from shortest to longest, lining up the ends first. Then mix them up and let your child put them in order again.
- Use a piece of yarn to compare things in different rooms, like the length of the couch and the width of a bed, and talk about how the yarn helped decide.
- Ask comparison questions on walks: "Is that stick longer or shorter than your arm? How could we check without moving the stick?"
Want a little more? Watch the kid-friendly video below together, or try Bobby's Math Club for free practice that adapts to your child.
Kid-friendly explanation
Questions parents ask
Why is my child comparing lengths without a ruler?
Comparing objects directly and with a third object teaches the logic that measuring depends on. A ruler is a tool for comparing an object to a known length, so understanding this idea first helps rulers make sense later. It also teaches careful habits, like lining up ends.
What does compare indirectly mean?
It means comparing two objects by using a third object in between. If your child cannot put a table and a door side by side, they can measure the table with a string, then hold the string against the door. Whichever is longer than the string is the longer one. This reasoning is the foundation of measurement.
What comes after ordering by length?
Next in 1st grade, children measure an object by laying shorter objects, like paper clips or cubes, end to end and counting how many fit. In 2nd grade, they measure with rulers, yardsticks, and measuring tapes in inches, feet, centimeters, and meters.
Make learning math fun
Bobby's Math Club turns 1st grade math practice into something fun to do together.
- Unlimited free practice
- Practice that starts where your child is and grows with them
- Hints when they are stuck, and a celebration when it clicks
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
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Join the clubNote for teachers: This skill is covered by Common Core math standard 1.MD.A.1: “Order three objects by length; compare the lengths of two objects indirectly by using a third object.” Learn how Bobby's Math Club can help your students grow. (Common Core 1.MD.1)