Try some yourself
Contour lines on a map show all the points at a given height above sea level. The lines are drawn for each height at 50-metre intervals, and points below sea level are shown by negative heights. The diagram below shows a peak with six such contour lines. The lines for −100, 0 and 100 have been labelled. Copy the diagram and label the other three contour lines.
You might like to make some notes on this section, perhaps in your, before moving on to the next section