Area of Composite Shapes for Kids: Split It Into Rectangles (Grade 3 Math)

Hi, I'm Luna from DoodleBeez. Today we are finding the area of shapes made from rectangles. Area is the number of square units that cover a flat shape. Some shapes look tricky, but we can break them apart.

First, a quick reminder. This rectangle has three rows with four squares in each row. Instead of counting every square, multiply. Four times three is twelve, so the area is twelve square units.

Here is an L shape. It is not a rectangle, so we cannot just multiply. But we can draw a line to split it into two rectangles. One is eight by three, and the other is three by four.

Now find each area and add them. Eight times three is twenty four. Three times four is twelve. Twenty four plus twelve is thirty six. The L shape has an area of thirty six square units.

There is another way. Imagine the whole big rectangle, eight by seven, which is fifty six. A piece five by four is missing, which is twenty. Fifty six minus twenty is thirty six. Same answer!

Area is always measured in square units, like square centimeters or square meters. A room shaped like an L can be split the same way to find how much carpet it needs.

Now it's your turn. A shape is made from a rectangle six by two and a rectangle two by three. What is its total area? Pause and try. Six times two is twelve. Two times three is six. Twelve plus six is eighteen square units.

Great job! Remember, split a tricky shape into rectangles, find each area, and add them. Or find the big rectangle and take away the missing piece. Practice perimeter and area in the Math Lab at doodlebeez.com. See you next time!