Step 7 Objective

Choose and use correctly symbols, diagrams and graphs. Present and interpret solutions/findings in the context of the original problem/task.


What if pupils find this a barrier?

diagram showing three lines crossing

Line Crossings

  • Draw three straight lines (line segments) so that some cross over each other.
  • How many crossings are there?
  • Try different arrangements of the lines. What is the maximum number of possible crossings?
  • Try using more lines.
  • Is there a rule for the maximum for any number of lines? If so, write it down.

Use the problem Line Crossings.

  • What does the table of results show?
  • Can you write this down?
  • How does it help us to see whether there are incorrect results?