Kindergarten · Measurement & Data
K.MD.A.2: Compare two objects with a measurable attribute
K.MD.A.2 is a kindergarten Common Core math standard in Measurement & Data. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
Directly compare two objects with a measurable attribute in common, to see which object has "more of"/"less of" the attribute, and describe the difference. For example, directly compare the heights of two children and describe one child as taller/shorter.
In plain words
Compare two objects with a measurable attribute.
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
Look at the red circle and the blue circle. Which circle is bigger?
- They are the same size.
- The blue circle
- The red circle
Where students can get stuck
- Comparing two pencils without lining up their ends, so the one sticking out further looks longer.
- Calling one child taller while they stand on tiptoe or on a step, instead of on the same floor.
- Describing the difference only as "big," instead of saying taller, longer, or heavier.
Effective teaching strategies
- Line up one end of two pencils on a flat surface and have students say which stretches past the other, so they compare from the same starting line.
- Stand two students side by side on the same floor, with no tiptoes or steps, and have them say who is taller and who is shorter.
- Give students a sentence frame such as “The pencil is longer than the crayon,” so they use comparing words like taller, longer, and heavier instead of “big.”
Units that teach this standard
Find where K.MD.A.2 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Comparing which is longer, taller, or heavier for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice measurement and data at home
In Bobby's Math Club, students practice at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free for every family.
See how it works for teachers
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.