Unit 7
Geometry.
Angles and parallel lines, triangles, the areas of polygons and the circle, Pythagoras, similar triangles, and volume.
Before this unit
The unit, lesson by lesson
Lessons
5 lessons · 27 practice questions · about 2 hours
Angles and triangles
Angles on a straight line and across a crossing, angles between parallel lines, and why the angles of every triangle add up to 180 degrees.
Area
Area counts squares: a rectangle, then a parallelogram, a triangle and a trapezoid cut and rearranged, and a circle unrolled into a strip.
Pythagoras' theorem
In a right triangle the squares on the two legs exactly fill the square on the hypotenuse: how to find a missing side, and how to tell whether an angle is right.
Similarity
Similar triangles: the same angles, every side multiplied by the same number, and the area by its square. And at the end, measuring a tree by its shadow.
Volume
Volume counts unit cubes: the area of the base times the height, for a box, a prism and a cylinder, and why a cube twice as big holds eight times as much.