First and last points to cover more than half the
graph paper in both directions unless prevented
by certain conditions specified in the question
Avoid awkward scales e.g. 2 cm is used to
represent 3 units making it impossible to read each
small square accurately.
Recommended scale – 2 cm to represent 1, 2, 5 units of
the variable (or 0.1, 20, 500 etc).
show the area covered by 1st and last points and
indicate at least 6 squares vertically and at least 5
Use sharp pencil to draw thin, neat and
smooth line or curve.
Best fit straight line or curve means
Passing through as many points as possible.
Equal points are on either side of line, for
points that do not pass through the line.
No point is too far from line or curve.
(Except anomalous points)
Extend line beyond first and last
points and the line should be as
long as possible.
Use a 30-cm long ruler for
practical to draw straight line.
Axes are correctly labelled with
correct physical quantities and units
(in solidus notation).
Use more markings to prevent wrong
reading of scale.
Plot a graph of Variable 1 (Vertical
Axis) against Variable 2 (Horizontal
Mark the data points clearly with
neat thin small crosses.
Points must be plotted according
to the values in the table. Read the
The triangle used should cover at
least half of the line drawn.
The triangle should be drawn in
dotted line and do not mark the
points used with crosses.
Indicate the coordinates to be used.
The coordinates must be on the line.
Do not use plotted/ data points to
calculate gradient. Use other
Show complete working as to how
gradient is obtained.
Values read from graph should be
according to the number of decimal
places of the scales used.
(no units for gradient, but
units required for R)
Gradient = 1.60
Using y = mx + c,
and the coordinates
0.75 = (1.60)(0.35) + c
c = 0.19