This website is the creation of two mathematics educators — Kara Imm and Rachel Lambert — who use number strings in our work, and who hope to share our ideas with others. We first became interested in strings at Mathematics in the City (MITC), a professional development center for teachers, where we learned how to  use them with our elementary and middle school students. MITC was founded by Cathy Fosnot, and is a collaboration between City College New York (City University New York) and the Freudenthal Institute in the Netherlands. The work of MITC includes an explicit emphasis on the role of realistic contexts — believable or imaginable situations to kids — in mathematical investigations. In addition, contexts are designed so that generalizable mathematical models, such as the open number line, will naturally emerge and be used by students.

We envision this site as a place where teachers, coaches and mathematics educators can find new strings, post strings, get feedback on design or number choice, and discuss the pedagogy of number strings. To contribute a string, just put it into a comment.  Or send us an email with your string and we’ll start a new post. Ultimately we want to build a string community — now folks from all around the planet — who simply love strings and are convinced of their power for all kids.


  1. rachel, your workshop was great today! i really appreciated your wealth of knowledge and your enthusiam for teaching math. look forward to checking your website and trying number strings with my students.

  2. Great idea for a webpage. I’m gonna have to brush off the old string book I have somewhere. I will certainly share this site with colleagues. I think homage needs to go to Willem Uttenbogaart, the Godfather of Number Strings. Keep up the god work!

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