OREGON MATH STANDARDS (2021): [3.GM]

2021 Oregon Math Guidance: 3.GM.C.7

  ODE and Oregon Math Project Logo

Cluster: 3.GM.C - Geometric measurement: understand concepts of area and relate area to multiplication and to addition.

STANDARD: 3.GM.C.7

 Standards Statement (2021):

Relate area to multiplication and addition. Use relevant representations to solve problems in authentic contexts.

  Connections:

Preceding Pathway Content (2021)

Subsequent Pathway Content (2021)

Cross Domain Connections (2021)

Common Core (CCSS)

(2010)

3.GM.C.6

4.GM.B.6, 5.NF.B.4

4.NBT.B.6

3.MD.C.7

3.GM.C Crosswalk

 Standards Guidance:

Terminology

  • The dimensions of a rectangle can be referred to as length and width OR base and height.
  • A square with side length 1 unit, called “a unit square,” is said to have “one square unit” of area, and can be used to measure area (e.g., square cm, square m, square in, square ft).

Teaching Strategies 

  • 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.
  • Multiply side lengths to find areas of rectangles with whole number side lengths in the context of solving problems, and represent whole-number products as rectangular areas in mathematical reasoning.
  • Use tiles and/or arrays to illustrate and explain that the area of a rectangle can be found by partitioning it into two smaller rectangles and that the area of the larger rectangle is the sum of the two smaller rectangles.
  • Recognize area as additive. Find areas of rectilinear figures by decomposing them into non-overlapping rectangles and adding.

Progressions

  • Students can be taught to multiply length measurements to find the area of a rectangular region. But, in order that they make sense of these quantities, they first learn to interpret measurement of rectangular regions as a multiplicative relationship of the number of square units in a row and the number of rows.
  • Students learn to understand and explain that the area of a rectangular region of, for example, 12 length-units by 5 length-units can be found either by multiplying 12 x 5 or by adding two products, e.g., 10 x 5 and 2 x 5, illustrating the distributive property. (Please reference pages 17-18 in the Progression document)

Examples

  • The area of a rectangle with whole-number side lengths a and b + c is the sum of a × b and a × c; 4 x 7 is the same as 4 x (2 + 5) and is the sum of 4 x 2 and 4 x 5.
  • In a rectangular garden, you have four rows of peanut plants. There are 9 peanut plants in each row. How many peanut plants are there in the garden?
  • Student Achievement Partners: