GRAPHING
Scientific Data on a Line Graph
You want to use as much of the graph as possible so that you can see
any patterns.
Let's do the xaxis first.

Count the number of lines the axis has: count like moving on a board game,
don't count the first line. On this graph there are 20 lines on the xaxis.

Determine the maximum value to be plotted on the xaxis. For this data
the maximum temperature was 80 ^{o}C.

Set up a ratio of maximum data value to number of lines:
=
this reduces to 4 ^{o}C for every 1 line

You probably do not want to label every line and there is really no use.
So let's label every 4 lines, that would be 16 ^{o}C for every
4 lines. But our data for temperature is every 20 ^{o}C, so we
probably want to label every 20 ^{o}C. In order to do this you
would label every 5 lines. The idea is to label the axis quickly and conveniently
without trial and error.

NOTE: The data used here is designed to work out in a nice reducible fraction.
If your ratio was not reducible to whole numbers simply divide out to get
a value, maybe it was 4.4274 ^{o}C for every 1 line. Simply round
up till you find something easy to use in scaling your axis. I would choose
4.5 ^{o}C for every line here, or 9 ^{o}C for every 2 lines.
I should be able to label fairly easily with those values.

Back to our example. Scale the axis:
Now do the same for the yaxis.