# Ellipses, coins, and fractals

Last Saturday we had the first of four Boise Math Teachers’ Circle meetings for 2016–2017. The four-hour session contained an in-depth look at three different math problems: one in geometry, one in number theory, and one in topology.

**Activity 1–Ellipses, by Joe Champion**. How can you draw an ellipse (oval) with two pushpins and a string? What happens if you increase the number of pins from two to three? or more?**Activity 2–Coins, by Laurie Cavey**. What amounts can you make with a 4-cent coin and a 7-cent coin? What amounts can’t you make? Is there a reason for the answers?**Activity 3–Fractals, by Sam Coskey**. We often think of a segment as being one-dimensional, a rectangle two-dimensional, and a box three-dimensional. Can there be figures that have a fractional dimension?