You will need five different colors and a straightedge.
On the circle below, draw the following sets of chords, each in a different color:
AI, BJ, CK, ..., RH.
AH, BI, CJ, ..., RG.
AG, BH, CI, ..., RF.
AF, BG, CH, ..., RE.
AE, BF, CG, ..., RD.
What do you notice about the finished picture?
AH, BI, CJ, ..., RG.
AG, BH, CI, ..., RF.
AF, BG, CH, ..., RE.
AE, BF, CG, ..., RD.