Examples of what pupils should know and be able to do
Without drawing the graphs, compare and contrast features of graphs such as:
y = 3x, y = 3x + 4, y = x + 4
y = x – 2, y = 3x – 2 and y = –3x + 4.
Probing questions
How do you go about finding the gradient for a straight-line graph
- that has been drawn on a set of axes?
- from the equation given in the form y = mx + c?
- from a table of coordinates?
What happens to the straight-line graph as m changes (increases, decreases, is negative)?
What happens as c changes?
How would you go about identifying the graph of y = 3x – 5 on a set of axes?
What if pupils find this a barrier?
Use and adapt the Wise words activity in Teaching mental mathematics: algebra on p. 21 - Acrobat pdf document (36Kb) Initially keep equations in the form y = mx + c.
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