Presenting results: line graphs, bar charts and averages

Which chart for which data

Use a bar chart when the thing you changed comes in separate categories (types of soil, colours). Use a line graph when it changes continuously (time, temperature, height). Choosing the wrong one loses marks even if every number is right.

Drawing a graph properly

Label both axes with the quantity and the unit. Choose a scale that uses most of the paper and goes up in equal steps. Plot the points, then draw a line of best fit if the pattern is clear — do not join every point with a zig-zag.

Averages

Repeat a measurement three times and take the mean: add the values and divide by how many there are. If one value is clearly odd, leave it out of the mean and say why — that is better science than including it silently.