3.17 describe experiments to investigate the refraction of light, using rectangular blocks, semicircular blocks and triangular prisms

Place a block of glass on a piece of paper, drawing an outline.
At one point, draw the normal line.
Draw a line at 30 degrees to the normal line, shine a ray of light down this line.
Draw a line where the light comes out the other side. Connect the two lines, drawing the refracted ray.
Measure the angle of the emergent ray.
Repeat for different shaped glass.