Coordinates and Straight-Line Graphs: Where to start

Put a dot on a grid, and two numbers tell you exactly where it sits: how far along, then how far up. Draw a straight line through dots like that, and two numbers describe the whole line. One says how steep it is. The other says where it crosses the y-axis. That is this chapter in two moves. Here is what matters in it, and which video to press first.

The chapter is built in layers. Each video stands on the one before it, so the list runs from a single dot to the hardest line. If you are not sure where you stand, start at the top of the list. Move on as soon as a video tells you nothing new.

If coordinates still feel shaky, start with Coordinates in Four Quadrants. Every course sets it, on both tiers. The common slip there is writing the two numbers the wrong way round. Coordinates from Geometric Information and Midpoints comes after that. Not every course sets it, so check your own before you spend the time. Where it is set, the midpoint caught out about two students in three on one paper. If you can plot a point but a whole line is new, go to Plotting Straight-Line Graphs. The main problem there is drawing the line without a table of values first. Finding the Gradient of a Straight Line is where steepness becomes a number, called the gradient. Writing that number with an x attached is a slip many students make. Gradient and Y-Intercept via y equals m x plus c reads both numbers straight out of an equation. The y-intercept is where the line crosses the y-axis. The same stray x turns up there too, even after a correct rearrangement. Finding the Equation of a Straight Line works the other way round, from a graph or two points to the equation. Negative numbers are where students struggle in it, in the gradient and in the intercept. Equations of Parallel Lines builds directly on that method, and it is a known weak spot. Equations of Perpendicular Lines comes last, and it is Higher only. Many students find the right line there, then slip on where it crosses the x-axis. You can find any video by its name, or by the code beside it on the list. The quickest way is the scholafly.com website, which indexes every video in every subject.

Next in the chapter is Coordinates in Four Quadrants. Hopefully that's next in your feed, but if not, search for ScholaFly M A fifteen, oh one.

Every other video is on scholafly.com too, easy to search by video code or by keyword. Whatever you're revising, go there and have a look, or, watch the next video.