|Subject:||the nine dots|
You can connect them without leaving the rectangle in four straight lines.
Suppose the rectangle is
A B C|
D E F
G H I
The solution is A->B-C->F->E->D->E->F->I->H->G.
Note that you can draw this without leaving the hand from the paper, but you have to draw on the line DEF twice. But the result is four straight lines.