CCSS.Math.Content.3.MD.C.7b
The standard
Multiply side lengths to find areas of rectangles with whole-number side lengths in the context of solving real world and mathematical problems, and represent whole-number products as rectangular areas in mathematical reasoning.
Common Core State Standards for Mathematics
What this standard means
Students need to find the area of rectangles by multiplying length times width. They should see the product as the number of square units in equal rows and columns, not just a rule to memorize. They also need to use rectangles to show multiplication facts and solve word problems.
Mastery looks like drawing or labeling a rectangle, choosing the correct side lengths, multiplying accurately, and naming square units. Students often mix up area and perimeter, forget units, or count only the outside squares. Some know the fact but cannot explain why it matches the rectangle.
Ways to teach it
- Give students grid paper and ask them to draw 3 by 7, 4 by 6, and 5 by 5 rectangles, then label each area.
- Ask students to explain in writing how a 6 by 4 rectangle proves that 6 times 4 equals 24.
- Show three labeled rectangles and ask students to write the multiplication equation and area for each one.
- Have students measure a book cover or desk top to the nearest inch, then estimate its area using length times width.
Plan a lesson for CCSS.Math.Content.3.MD.C.7b
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Related standards
- CCSS.Math.Content.5.NF.B.4b
Find the area of a rectangle with fractional side lengths by tiling it with unit squares of the appropriate unit fraction side lengths, and show that the area i...
- CCSS.Math.Content.3.MD.C.7a
Find the area of a rectangle with whole-number side lengths by tiling it, and show that the area is the same as would be found by multiplying the side lengths.
- CCSS.Math.Content.3.MD.D.8
Solve real world and mathematical problems involving perimeters of polygons, including finding the perimeter given the side lengths, finding an unknown side len...
- CCSS.Math.Content.4.MD.A.3
Apply the area and perimeter formulas for rectangles in real world and mathematical problems.