1st Grade Measuring Length Lesson (Free PDF)
This measuring length lesson for 1st Grade covers measuring length (Common Core 1.MD.A.1, 1.MD.A.2), with a free PDF to print.
Length tells how long an object is. To measure length, lay same-size units, such as cubes, end to end along the object. Leave no gaps and make no overlaps. Start at one end and count the units. The number of units is the length. To compare objects, line up their left ends and see which one reaches farther.
Grade 1 · Common Core State Standards: 1.MD.A.1, 1.MD.A.2
Key facts in this measuring length lesson
- Length is how long an object is from one end to the other.
- Line up the left ends to tell which of two objects is longer.
- Units must be the same size, laid end to end, with no gaps and no overlaps.
- The count of units is the length, and the unit name goes with the number.
- If A is longer than B and B is longer than C, then A is longer than C.
What is length?
Length tells how long something is. A crayon, a rope, and a school bus all have a length. Some things are long. Some things are short.
How do you compare and order objects by length?
Put the objects side by side. Line up the left ends on the same starting line. Then look at the right ends. The object that reaches farther is longer.
The marker is the longest. The crayon is the shortest. From shortest to longest the order is crayon, pencil, marker.
Sometimes two objects are far apart and cannot sit side by side. Use a third object to help. If a scarf is longer than a belt, and the belt is longer than a shoelace, then the scarf is longer than the shoelace.
How do you measure length with units?
- Pick one kind of unit. All the units must be the same size.
- Start at the left end of the object.
- Lay the units end to end. Leave no gaps and make no overlaps.
- Count the units. Say the number and the unit name.
Example. A paintbrush has 7 cubes laid along it with no gaps. The paintbrush is 7 cubes long. We can write \(7\) cubes.
What mistakes should you avoid?
- Do not leave gaps between the units.
- Do not stack units on top of each other.
- Do not start the row away from the left end of the object.
Do big units and small units give the same number?
No. A small unit needs more copies to cover the same length. Here the ribbon is 4 big cubes long. It is also 8 small cubes long. Always say the unit name, and use the same unit when two objects are compared.
If one pen is \(8\) cubes long and another pen is \(5\) cubes long, then \(8 > 5\), so the first pen is longer.
Measuring length lesson: questions and answers
What does length mean in first grade math?
Length is how long an object is from one end to the other end. First graders compare lengths, order objects, and measure with small same-size units.
How do you measure length with cubes?
Start at the left end of the object. Lay cubes end to end with no gaps and no overlaps. Count the cubes. If there are 7 cubes, the object is 7 cubes long.
Why must all the units be the same size?
Different sizes make the count unfair. Two objects can only be compared by counting when the same kind of unit is used for both.
How do you order three objects by length?
Line up the left ends of all three. Find the object that reaches farthest, the one that reaches least, and the one in the middle. Then name them from shortest to longest or the other way.
How can you compare two objects that cannot touch?
Use a third object. If the first is longer than the third, and the third is longer than the second, then the first is longer than the second.
How to use this measuring length lesson
Read the definitions first, then follow the worked method line by line and redo the example on paper without looking. When every step makes sense, move on to the worksheet, then check yourself with the quiz.
Download the measuring length lesson as a PDF with the button below and keep it with your notes.
Download the measuring length lesson as a PDF with the button below and keep it with your notes.
All Grade 1 chapters: Grade 1 math.
