Friday
Friday: Shapes All Around
Rocket points at the garage door. "Rectangle." At the roof. "Triangle." At a floor tile Raven is holding. "Parallelogram!"
"What do you notice about the window?" Raven asks. It is a rectangle with a triangle on top.
"A house shape," Rocket says. "Two pieces. Rectangle plus triangle. Add them."
Nova hovers at the window, her light tracing the edge where the two shapes meet. "Every flat shape is pieces," she says.
"So the floor plan was practice for everything," Raven says. "Kites, tiles, roofs, signs."
Rocket is already sketching. "Next week we tape a grid on the floor and lay out the walls with string."
Nova hums. "Coordinates," she says. "Bring the tape."
Everyday cut-and-compose
| Thing | Pieces | How to find the area |
|---|---|---|
| A kite | two triangles | half × base × height for each, then add |
| A house-shaped window | a rectangle and a triangle | base × height, plus half × base × height |
| A floor tile | a parallelogram | base × straight-across height |
| A garden bed with a slanted end | a trapezoid | half × (top + bottom) × height |
| An L-shaped room | two rectangles | cut it, find each, add |
Every flat shape with straight sides is made of rectangles and triangles. When you see one, look for the cut.
The height is always the straight-across distance. A slanted side is never the height.
How to find any area
- Cut the shape in your head into rectangles and triangles. Draw the cut lines.
- Find the base and the straight-across height of each piece.
- Use the formula for each piece: base × height, or half of it for a triangle.
- Add the pieces. Write the units: square centimeters, square meters or square units.
- Read the question.
- Tap your answer.
A floor tile is a parallelogram with base 10 cm and straight-across height 8 cm. What is its area in square centimeters?
A garden bed is a trapezoid: top 5 m, bottom 9 m, height 4 m. What is its area in square meters?- Read the question.
- Tap your answer.
What is the area of the parallelogram in square centimeters?
What is the area of the triangle in square centimeters?
What is the area of the trapezoid in square centimeters?
What is the area of the polygon in square units?| Week review | True or false? |
|---|---|
| The area of a parallelogram is base × height. | ? |
| The area of a triangle is base × height. | ? |
| A trapezoid is two triangles with the same height. | ? |
| The slanted side of a parallelogram is its height. | ? |
| Any polygon can be cut into rectangles and triangles. | ? |
- ?We cut a parallelogram and slid it into a rectangle: base × height.
- ?We fitted two triangles into a parallelogram and cut a trapezoid into two triangles.
- ?We ran Build Lab and counted squares to check every formula.
- ?We added up the four rooms of the clubhouse floor plan and decomposed the L shape.
Cut each sketch into rectangles and triangles. Mark where you would measure the base and height.
A week of cuts and squares. Tomorrow is Build Day: find and measure a real floor shape with your family.