On a $4$ by $4$ geoboard (say) - how many different sized squares can you make using rubber bands? How could you make a square with NO pins along a side (an edge) and just the 4 pins at the corners (vertices)? The basic unit of measurement is one square unit (as shaded in the diagram). How can you make a square whose area is 2 square units? Can you make a square with an area of 3 square units?