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Area and perimeter formulas poster (free printable)

Six formulas for the flat and solid shapes in grades 4 to 8, each beside what it finds. Edit the list to the formulas your grade uses, then post it in the geometry corner.

Printed on the sheet. Leave it empty to write by hand.
To find | use
Colour
Shape Formulas, page 1Shape FormulasTo findUsearea of arectanglelength × widthperimeter of arectangle2 × (length +width)area of atriangle½ × base ×heightarea of a circleπ × radius ×radiuscircumference ofa circle2 × π × radiusvolume of a boxlength × width ×height

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About this sheet

A formula is a shortcut for something children could count. Area counts the square units that cover a flat shape, perimeter counts the length around the edge, and volume counts the cubes that fill a box. Each row on this poster names what you want to find on the left and gives the rule for it on the right, using the multiplication and division signs that children see in class. The six defaults cover the rectangle, the triangle, the circle and the box. Because the units differ, a short reminder helps: area is in square units, volume is in cubic units, and perimeter is in plain units. Edit the list to match the work of your grade, and keep the counting experience first.

Grades: 4 to 8.

How to use it

  1. Choose which of the six formulas your class needs this term and rewrite any that use a different symbol or wording.
  2. Print the poster and place it beside the graph paper and the array grids, where children first count squares.
  3. Before using a formula, have children count the squares or the edge by hand once, then confirm the rule gives the same number.

Five ideas for class

  1. Cover a rectangle on grid paper with squares, count them, and then find the same number by multiplying length by width.
  2. Walk a string around the edge of a desk, straighten it against a ruler, and compare the length with the perimeter formula.
  3. Cut a rectangle along its diagonal into two triangles, and ask why the area of each is half of base times height.
  4. Trace a round lid, measure across it, and ask children to use the circle rule to estimate how long a string around it would be.
  5. Build a box from cubes in layers, count one layer, multiply by the layers, and see where length times width times height comes from.

Related

Questions

What is the difference between area and perimeter?

Area is how much surface a shape covers, measured in square units. Perimeter is the distance around the outside, measured in ordinary units like centimeters or feet.

Should children memorize the formulas?

Understanding comes first. Many tests give a formula sheet, but children who know where a rule comes from can rebuild it, and the poster helps them check.

Can I use it with a calculator?

Yes, especially for the circle formulas, where pi makes the numbers awkward. Agree on whether to use 3.14 or the pi key, and write that on the poster.

How do I save it as a PDF?

Choose Print, then pick “Save as PDF” as the printer. Only the sheet prints: the page around it is hidden. You can also save a sheet as a PNG image under the preview.

Can I print it in black and white?

Yes. Switch to Black and white beside the sheet: fills turn white and lines turn black, so it saves ink and photocopies cleanly.

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