Roxanne, a fourth grade teacher from Toledo, sent me this problem. There is often more than one way to draw a solution to a problem. I always just look for a solution that the students have labelled, can explain, and makes sense to them.
I could have also drawn a unit bar, divided into fifths, than divided each section into three parts. That would have achieved the same thing. I love having multiple, visual approaches--and of course, it aligns to the practice standards of the Common Core State Standards for Mathematical Practices!