9 dot puzzle

[classact524]

This is a 3x3 dot puzzle that my son says can be solved with four lines that donot intersect. HELP!

[Harley]

Draw round the edges?

[DOB]

If the puzzle is the one where you have 3 lines of 3 dots which make a perfect square and you must cross over all 9 dots using only 4 lines, I don't think it can be done without 2 of the lines intersecting.

[cowpat]

Can't be done without crossing but look at this http://www.brainstorming.co.uk/puzzles/ninedotsnj.html