3.MD.6: Measure Area by Counting Unit Squares
Also written as 3.MD.C.6 and CCSS.MATH.CONTENT.3.MD.C.6 · Cluster: Geometric measurement: understand concepts of area and relate area to multiplication and to addition.
The Official Wording
Measure areas by counting unit squares (square cm, square m, square in, square ft, and improvised units).
Common Core State Standards, Grade 3, Measurement & Data · Read it at the source · Checked October 14, 2026
What 3.MD.6 Means in Plain English
Third graders measure surfaces by counting squares and naming the unit: a sticky note covers 9 square inches, and the reading rug covers 24 floor tiles a foot on each side, so 24 square feet. Improvised units count too, like the index cards it takes to cover a desk.
There is no formula yet, so every square gets counted, often row by row. The unit matters as much as the count: 13 square centimeters is not 13 square inches. Next, 3.MD.7 turns rows of squares into multiplication, and 4th grade uses the formula to find missing sides (4.MD.3).
3.MD.6 I Can Statements
- I can count unit squares to find the area of a shape.
- I can name the area unit, like square centimeters or square feet.
- I can choose a sensible square unit for a desk or a floor.
3.MD.6 Worked Example
A T-shaped tile traced on centimeter grid paper, counted square by square and named in its unit.
Ava traces a T-shaped tile on centimeter grid paper. The top bar is 5 squares across and 2 squares tall. The stem under it is 1 square across and 3 squares tall. What is the area of the tile?
- Name the unit first. Each grid square is 1 centimeter on every side, so each one is 1 square centimeter.unit: square centimeters
- Count the top bar one row at a time so no square is counted twice.5 + 5 = 10
- Count the stem, starting under the bar, not inside it.1 + 1 + 1 = 3
- Add the two counts and write the unit with the number.10 + 3 = 13 square centimeters
Check it: Number the squares 1 to 13 as you shade them. Every square has exactly one number, and none is left blank.
Common Mistakes with 3.MD.6
A number with no unit
The T’s area written as 13, or as 13 centimeters
Try this: Ask what was counted. The answer is squares, so the unit is square centimeters, because centimeters alone measure length, not area.
Counting the stem through the bar
The stem counted from the top of the T, 5 squares tall, so the area comes out as 15
Try this: Shade or number each square as it is counted, so every square gets exactly one mark and the overlap shows.
A unit that does not fit the job
The classroom floor measured in square centimeters, a count in the hundreds of thousands
Try this: Hold up a square centimeter and a square-foot floor tile, then pick the unit that suits the surface before counting begins.
Where 3.MD.6 Fits
Practice 3.MD.6
Quick Check
- A sticky note is covered by 3 rows of 3 one-inch squares. What is its area?
- Which unit fits the area of a classroom floor better, square centimeters or square meters?
- A shape on centimeter grid paper has 4 rows of 5 squares, plus 3 more squares below. What is its area?