What this lesson shows
A 6 by 9 rectangle, then one where area is known and a side is not.
The worked example
The lesson works this one step by step: 9 by 6. Then your kid tries one like it on paper.
The steps
- Perimeter: add the sides
- Area: length × width
- A missing side is n
- Say the units
Helping at home
Perimeter is the distance around the edge: add all four sides, in feet. Area is how many square feet cover the inside: multiply the length by the width. With the area and one side, write the other side as n and divide. Say the units every time.
If your kid gets stuck
Around the edge, or covering the inside?
Watch it with Lux
With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.
Standards
- Common Core 4.MD.A.3
Apply the area and perimeter formulas for rectangles in real world and mathematical problems. For example, find the width of a rectangular room given the area of the flooring and the length, by viewing the area formula as a multiplication equation with an unknown factor.
Matches standards in 48 statesSee each state's code
- Alabama MA19.3.24, MA19.4.23
- Alaska 4.MD.3
- Arizona 4.MD.A.3 *
- Arkansas 4.GM.7
- California 4.MD.A.3
- Colorado 4.MD.A.3
- Connecticut 4.MD.A.3
- Delaware 4.MD.A.3
- District of Columbia 4.MD.A.3
- Florida MA.4.GR.2.1, MA.4.GR.2.2
- Georgia 3.GSR.8.2, 4.GSR.8.3
- Hawaii 4.MD.A.3
- Idaho 4.MD.A.3
- Illinois 4.MD.A.3
- Indiana 3.M.5, 4.M.4
- Iowa 4.MD.A.3
- Kansas 4.MD.3
- Kentucky KY.3.MD.8.c, KY.4.MD.3
- Louisiana 4.MD.A.3
- Maine 4.MD.A.3
- Maryland 4.GR.A.3
- Massachusetts 4.MD.A.3
- Michigan 4.MD.A.3
- Mississippi 4.MD.3
- Missouri 3.GM.D.16, 4.GM.C.8
- Montana MT.4.MD.3
- Nebraska 4.G.3.a
- Nevada 4.MD.A.3
- New Hampshire 4.MD.A.3
- New Jersey 4.M.A.3
- New Mexico 4.MD.A.3
- New York NY-3.MD.8.b, NY-4.MD.3
- North Carolina NC.4.MD.3.b, NC.4.MD.3.c
- North Dakota 4.GM.M.5
- Ohio 4.MD.3
- Oregon 4.GM.B.6
- Rhode Island 4.MD.A.3
- South Carolina 4.MGSR.1.1, 4.MGSR.1.2
- South Dakota 4.MD.A.3
- Tennessee 4.MD.A.3
- Texas 111.6.b.5.C, 111.6.b.5.D, 111.7.b.4.H
- Utah 4.MD.3
- Vermont 4.MD.A.3
- Virginia 4.MG.3a, 4.MG.3b, 4.MG.3c, 4.MG.3d, 4.MG.3e, 4.MG.3f, 5.MG.2f, 5.MG.2g
- Washington 4.MD.A.3
- West Virginia M.4.21
- Wisconsin M.4.MD.A.3
- Wyoming 4.MD.3