I found this note when I was cleaning out some old papers. It’s like finding a strange little gift from the us of the past. List of Counterexamples Communism Hitler Klein 4 group Petersen graph Plasma Hawaii Neutrinos Tacoma Narrows bridge Rwanda The 1% Duck-billed platypus Seahorses

## Announcements

Note: The Math for Love newsletter does not usually get posted on the blog. If you’d like to sign up, enter your name and email in the sidebar. Here are the announcements from our last one. A Coin Problem I’ve posted one of my favorite problems of all time as this week’s NYTimes Numberplay puzzle. Consider this simple game: flip …

## A dollar that costs a dollar

I had one of those awesome experiences this week where a student thinks of a better question. I had been playing around with this issue of what money costs to make. (Get the lesson here.) Not a pretty picture, by the way. Rounding only a little for simplicity and age appropriateness, we had this chart of costs: Penny: 2.5 cents …

## Who is the most famous?

One fun thing math lets us do is measure difficult-to-measure things. Like fame. We all have an instinct for what fame is, and the more we put it into words, the more we’ll find we can translate fully into math. So what let’s us know if someone is famous? Well, famous people are well known. We tend to know them, …

## A Math Menu for Fraction Division

I’m not sure who came up with the idea of “Menus” as a math teaching device, though I first saw them at a workshop from the folks at MEC. Menus are essentially modified stations, designed to be a several-day structure that puts kids at the center of their own learning process. After a brief launch from the teacher, the students …

## 1-2 Nim Write Up

I’ve been taking some time to write up some lessons, and I’d love to get some feedback. You can click here for a pdf of this lesson on 1-2 Nim. It’s one of our favorites: a surefire way to get students of any age playing and thinking. The question is: how’s the write up? We’ve been shooting for 1-2 pages maximum, so …

## The Mathematically Inclined Shall Inherit the Earth

“… at this point, it’s in the hands of people who are mathematically inclined.” —Stephen Hsu The January 6th New Yorker contains an article on B.G.I., a Chinese company seeking to do major work in the field of genetics. According to them, the massive amounts of genetic data they (and others) are collecting and interpolating will help “explain the origins …

## Deeper questions with percents

The good thing about teaching percents is that they connect to the real world, particularly with money. The bad thing is, it can be hard to find really dynamic problems. Too often, you’re just marking prices up or down in imaginary shops, or looking for discounts at imaginary sales. Not a bad thing to be able to do, but not …

## Harmonic Puzzle

One of the beautiful results in mathematics is the proof of the divergence of the harmonic series. What it tells us is that the infinite series of fractions 1/2 + 1/3 + 1/4 + 1/5 + 1/6 + … gets infinitely large. Recently, I got to wondering which numbers it hits on the way up. In particular, if you can …

## Seeds and Stalks

The grails of math activities, for me, are those that involve almost no special knowledge to get into, but have near-infinite depth. (Like this one.) We sometimes describe them as having a short barrier to entry, and no ceiling. (A common suggestion when we work with teachers is to “remove the ceiling,” that is, find ways to change the problem …