Fridge Formulas

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What You Need:

  • Black marker
  • Red marker
  • Paper and pencil
  • Magnet

What You Do:

For example:

The formula for finding the area of a rectangle is “area equals length times width” or A = L x W

Draw a rectangle and label the sides: L=6, W=2

Some common middle school formulas include:

Perimeter = L + L + W + W

Area of a:

  1. Check with your child’s math teacher to find out which formulas the class will be studying in geometry.
  2. Choose one formula. On white paper, write the formula in red marker and, in black marker, draw and label a figure.
  3. On Monday, post the “Fridge Formula” on the refrigerator and ask your child to solve it by the end of the day. Every day that week, write the same formula, but draw a figure with different measurements. Have your child apply the formula and “post” an answer by the end of each day.
  4. The following week, choose a new formula and repeat the process.
    • Rectangle: L x W
    • Square: B x H
    • Triangle: ½ B x H
    • Circle: π r²


Challenge your child to “race” an older sibling. The first to post an answer to the “Fridge Formula” wins!

Copy each formula (in red marker) onto a 3x5 notecard. Make room on your refrigerator for each formula and leave them up for the entire quarter. Everyone might get tired of seeing them, but once the formulas come down, it will be hard to forget them!

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