Draw the rectangle around the triangle and find its area. The triangle covers exactly half, so divide by 2: a 3 by 2 rectangle is 6 square units, so the triangle is 3.
basethe side the triangle sits on
heightstraight up from the base to the top point
areathe space inside a flat shape
square unitswhat area is measured in
Watch for: Forgetting to divide by 2. Using a slanted side as the height. Writing the answer without square units.
At home: Cut a paper rectangle from corner to corner and lay the two triangles on top of each other: each is half the rectangle.
Sample sheet and answer key
Luna's Space Adventure
Grade 4 · Area of triangles · 4.GR.A.4
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Half a rectangle
Find the rectangle's area in square units. The triangle is half of it.
RectangleTriangle
RectangleTriangle
RectangleTriangle
Base times height, halved
Area = base × height ÷ 2, in square inches.
Triangle
Triangle
Triangle
Base, height and area
Each is base × height ÷ 2 = area. Find the missing number.
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
