Step 3 Objective

Begin to refine ways of recording and use appropriate mathematical symbols correctly.

Examples of what pupils should know and be able to do

a diagram with a two by two grid and a two by three grid

Shading Squares
There are six different ways to shade two squares in this shape. Can you find them all?

 

What about this shape?

How many ways are there?

Try using different rectangles made up of more squares.

Try shading three squares.

Examples drawn from Shading Squares

Find 10 or more of the arrangements for two squares out of six without any repeats.

Ten or more of the arrangements for 2 squares out of 6 without any repeats.

Probing questions

Which methods of organising information have you found most helpful?

How is this different from the way you have recorded information before?

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.

  • Draw other diagrams using only four (or five) lines; how many different numbers of intersections (crossings) can you get?
  • How many more diagrams with a different number of intersections can you draw using four (or five) lines?
  • How might you record the maximum number of crossings for three, four, five lines?
  • Are there other ways?