Step 5 Objective

Begin to structure an approach when exploring a simple task or solving a problem. Generate and check the necessary information.


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.

  • Are you sure that you have all of the different arrangements for four, five lines?
  • How can you be sure?
  • What different types of arrangement are there for five or six lines?