Algebra · Straight-line graphs
Chapter 1 · 3
The idea
Coordinates and midpoints (four quadrants, missing corners, ratio on a line)
How two numbers in brackets pin down a point in all four quadrants (across first, then up or down), lines where one coordinate never changes, how to find the missing corner of a shape, the midpoint of a line segment and the other end from a midpoint, and how to find the point that splits a line segment in a given ratio.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Algebra · Straight-line graphs
Coordinates and midpoints (four quadrants, missing corners, ratio on a line)
How two numbers in brackets pin down a point in all four quadrants (across first, then up or down), lines where one coordinate never changes, how to find the missing corner of a shape, the midpoint of a line segment and the other end from a midpoint, and how to find the point that splits a line segment in a given ratio.
Why it works
Two numbers that pin down a place
A plan of a park is drawn on a square grid. The café sits where the two axes cross, a point called the origin, O. Every other place in the park is given by two numbers in brackets, its coordinates.The gate G is at . Start at O, go across to the right, then up. The first number is always the move across, the -coordinate. The second is the move up, the -coordinate. To plot a point, make the same two moves and mark it with a small cross.
Keep reading — free
The rest of the explanation, plus 5 worked examples you step through move by move.
Start freeTakes a minute — no card.