intersections

what fractions or ratios (lengths) do the lines cut each other in?

what other fractions can be obtained by two intersecting diagonals of a trapezium (trapezoid) on a 5 by 5 dotty grid?

alternatively, focus on the four areas formed - what are they?

Dan Meyer has a great video clip that sets this up dynamically; moving from four equal sections (25%) each to a line that joins a corner to half way along a side (as in the example above) - inviting students to establish the areas as percentages of the whole
I'd rather use fractions...