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Ontario · Ontario Math · Grade 4

E2.5: Use the rows and columns of an array to measure the area of a…

Use the rows and columns of an array to measure the area of a rectangle, and show that the area of any rectangle can be found by multiplying its side lengths.

The Ontario Mathematics, Grades 1–8 outcome E2.5 (Spatial Sense) for Grade 4 says: “Use the rows and columns of an array to measure the area of a rectangle, and show that the area of any rectangle can be found by multiplying its side lengths.” This Fieldbook unit teaches it hands-on, with everyday materials and a printable teacher guide and student sheet for every lesson. Official wording: Ontario Mathematics, Grades 1–8.

Fence It, Fill It: Area and Perimeter Grades 3–4

Which mat is really the biggest? Does the same fence always hold the same garden? Can the same rug need more edging? Four lessons where students tile, stretch rope and chalk the schoolyard to find out that area and perimeter measure different things.

  • Which mat is the biggest? 50–60 min

    Teams cover three taped mats with sticky notes and find that the long, thin mat that looks biggest is the same size as a small square one. Students explain area as the number of unit squares that cover a shape, and find it faster by multiplying rows by columns.

  • Can the same rug need more edging? 45–60 min

    Teams build every rectangle they can from the same 24 square tiles and find that the edging around them runs from 20 to 50 tile edges. Students explain that the same area can have different perimeters, and use length × width = area to find a missing side.

Printable practice for E2.5

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Compared with Common Core: 3.MD.C.7.

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