San Francisco Math Circle & JRMF. (2020). River Crossing Problems. In S. Bowen (Ed.), Math Circle Activity Database. American Institute of Mathematics.

Humans, Zombies, & Other Problems Crossing the River

A town faces an epidemic of zombies! Luckily, the virus has just started to spread and the infected are able to stave off their hunger for human brains… for now. In fact, they’re willing to work alongside the remaining humans to help them get across a river to safety. Can you get all the humans and zombies across safely?

Activity Guide

This guide looks at the activity in detail and goes into the underlying math.

Desmos Activity

Students can work through the activity and answer questions. Teachers can assign work to students, view work, and control activity pace.

Digital App

This app created by JRMF and the San Francisco Math Circle contains Humans & Zombies and many other river crossing problems.

Photos & Videos