Using only 3 straight lines and without lifting your pencil, can you connect all the dots?
Nine dots are placed in three rows of each three dots, as shown in the picture. These nine dots must be connected by four straight, connected lines (i.e. without 'lifting up the pen' in between).
Can you copy the following image without lifting the pan from the paper?
Using points, straight lines, and possibly the curve of a parabola, construct a piecewise function whose graph looks like a smiling face.