This article describes three challenging yet accessible mathematics courses designed for middle school teachers and offered by the Department of Mathematics at the University of Nebraska-Lincoln (UNL). Their descriptions are based on the courses as we have taught them as part of the Math in the Middle (M2) Institute Partnership, a National Science Foundation Math Science Partnership (MSP) program that works with practicing teachers. As a grant funded MSP, we take seriously the responsibility to share information about our program and the courses we have created. Readers are directed to our website [1] for information about our program and specifically to our course materials [2] for a link to additional information about the courses described in this article as well as other courses that we offer.

The aim of the M2 Institute, and the university—public-school partnership that created it, is to develop intellectual leaders in middle level mathematics (grades 5–8). A core strategy that guides Math in the Middle is to offer teachers content rich mathematics courses that are accessible and useful. Practicing teachers who are admitted to the M2 Institute earn 36 graduate credit hours over several years, resulting in a Master's Degree. More information on the M2 Institute is in the companion article [3] in this volume.

We describe three Math in the Middle courses: Mathematics as a Second Language (MSL), Experimentation, Conjecture and Reasoning (ECR), and Number Theory and Cryptology for Middle Level Teachers (NT&C).