Have you ever tried to list out all of the rational numbers? In this lesson we explored a nifty way of writing all rational numbers called the Calkin—Wilf tree. Continue reading A tree of fractions

# All posts by Samuel Coskey

# The logic of calculators

How can a calculator use the flow of electricity to add two numbers together? In this activity we explored the building blocks of electrical circuits, and the mathematical logic that lies behind it.

# Parametric equations

In this activity we explored periodic parametric curves. We particularly studied the patterns that arise when you change the periods of the $x(t)$ and $y(t)$ coordinates. To start playing around with parametric curves, you will need geogebra. Then you can use the following link to download our geogebra worksheet!

# Bart vs Lisa vs Fractions

Bart and Lisa compete in a two-day spelling contest. On the first day, Lisa gets a higher percentage right than Bart. And on the second day, Lisa gets a higher percentage right than Bart. So why did Bart win?? Continue reading Bart vs Lisa vs Fractions

# Mental math, version two

What do you mean you can’t do that in your head?! In this session we had fun learning how to do a lot of handy calculations. Each trick has a simple algebra rule behind it. Check out our handout! Continue reading Mental math, version two

# Math Teacher’s Circle–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. Continue reading Math Teacher’s Circle–Ellipses, coins, and fractals

# Adding together infinitely many numbers

It is often necessary to add more than two numbers together. For example, you might have made 137 deposits to your bank account this year, and wonder how much you contributed in total. But is it possible to add infinitely many numbers together? The answer is that sometimes it is possible, and sometimes it isn’t! In this discussion we investigated when, why, and how! Continue reading Adding together infinitely many numbers

# Boise Math Teachers’ Circle recruiting for 2016-2017

The Boise Math Teachers’ Circle is excited to announce our program for the 2016–17 school year! The BMTC is open to K–12 mathematics educators. We will meet four Saturdays, for four hours each, to discover exciting math concepts and tackle challenging math problems together.

### Our session dates

- Saturday, October 22, 2016
- Saturday, January 21, 2017
- Saturday, February 25, 2017
- Saturday, April 15, 2017

# Ovals upon ovals!

A circle has a center c and a radius r. The points on the circle are all a distance of exactly r units from c. What if we start with **two** fixed center points? The set of points on an **ellipse** have a fixed sum-distance to two center points c1 and c2 (called foci). An ellipse has kind of an oval shape. Ellipses occur in nature – the Earth’s orbit is not a perfect circle but rather an ellipse, with the Sun being just one of the two foci.

In this activity we investigated how to draw ellipses using pushpins and string. We also asked whether it is possible to have more than two fixed center points. Continue reading Ovals upon ovals!

# Mars moon mission

Suppose you are sending a crew of scientists to the moons of Mars: Phobos and Deimos. The scientists are botanists, geologists, and mathematicians, or any combination of the three. You want to divide the crew into to halves so that each moon gets an equal number of each scientists. When can this be done? Continue reading Mars moon mission