Interpreting Graphs 1

Graphs show the relationship between two variables. The independent variable is the one the investigator changes. It is plotted on the x-axis (horizontal).The dependent variable is the one that is measured. It is plotted on the y-axis (vertical).Each axis must have a label and units, for example "Temperature / °C". The scale should be even and use more than half of the grid.Data points are plotted accurately with small crosses. When both variables are continuous, a line graph is drawn. Points may be joined with straight lines, or a smooth line of best fit may be drawn if a clear trend is expected.Before interpreting a graph, always read the axis labels and units, and check whether each axis starts at zero.Example: in an investigation of the effect of light intensity on the rate of photosynthesis, light intensity is on the x-axis and the rate (for example, volume of oxygen produced per minute) is on the y-axis.