This lesson idea from Bob Lochel has students drawing chips (poker kind, not potato kind) from a brown bag and making predictions from the results.
As an aside, I once saw a similar activity at our Teacher’s convention, but the teacher substituted a rigged paper bag and enlisted the help of one devious student. The bag had a small window of cellophane taped in the back, and the student proceeded to “randomly” draw the same colour over and over again to the amazement of his classmates.