Measure areas by counting unit squares (square cm, square m, square in, square ft, and improvised units).
Official wording from the Common Core State Standards for Mathematics (Β© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org
Once students know that area means covering with unit squares, they put it into practice by actually counting. Shapes drawn on centimeter grid paper, rooms measured with square-meter mats, desktops covered with square sticky notes: each is an area measured by counting how many square units fit. The units can be standard (square centimeters, square meters, square inches, square feet) or improvised, like squares cut from cardboard.
Choosing and naming the unit is part of the skill. A book cover suits square inches or square centimeters, while a classroom floor suits square feet or square meters. Students should notice that a smaller unit gives a larger count for the same surface, because more of the small squares are needed. Counting carefully also matters for shapes that are not rectangles: students organize their count by rows or by splitting the shape into parts so that no square is missed or counted twice. These counting experiences are what make the multiplication method in 3.MD.C.7 make sense.
On irregular shapes, students often lose track and count some squares twice. Encourage marking each square as it is counted or counting row by row.
Students may think 40 square inches is more than 2 square feet. Compare the sizes of the units before comparing numbers.
An answer of 18 does not say whether it is square centimeters or square feet. Require the unit with every area.
Some students count the lines on grid paper instead of the squares between them. Shade squares to make the count visible.
A shape on centimeter grid paper has a top row of 6 squares, a middle row of 6 squares and a bottom row of 3 squares. What is its area?
Answer: The area is 15 square centimeters.
Let students measure the same surface with two sizes of improvised unit, such as large and small sticky notes, and discuss why the counts differ. Then introduce standard units with grid paper and square-foot tiles. A classroom hunt for surfaces measured in different units builds a sense of size.
Assessment items present shapes on grids, sometimes non-rectangular, and ask for the area with units. Some ask which unit is best for a given surface.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: 14 (also accepted: 14 square centimeters)
Count the squares: 7 + 7 = 14 square centimeters.
Answer: C) square meters
A classroom floor is large, so square meters (or square feet) give a sensible number.
Answer: 11 (also accepted: 11 square units)
Add the rows: 4 + 4 + 2 + 1 = 11 square units.
Answer: A) A larger count, because each small note covers less
Smaller units cover less surface each, so more of them are needed for the same desk.
Answer: 9 (also accepted: 9 square feet)
3 rows of 3 tiles is 9 tiles, so 9 square feet.
Answer: C) Something like the perimeter, not the area
Counting lines around the edge measures distance around the shape. Area counts the squares inside.
Partition a rectangle into rows and columns of same-size squares and count to find the total number of them.
A full lesson with slides, activities and an exit ticket on measuring area by counting unit squares, pitched to grade 3 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on 3.MD.C.6 with an answer key, ready in about a minute.
Make a worksheet βTurn measuring area by counting unit squares into a quiz students answer online that marks itself, with a class summary for you.
Build a test βSquare centimeters, square meters, square inches, square feet and improvised units.
Counting builds the understanding that area is a number of square units, which is what makes the multiplication method meaningful in 3.MD.C.7.