Mathematical models are conceptual processes that use mathematics to describe, explain, and/or predict the behaviour of complex systems. This article is written for teachers of mathematics in the junior secondary years (including out-of-field teachers of mathematics) who may be unfamiliar with mathematical modelling, to explain the steps involved in developing a model and the differences between modelling and traditional problem solving. Two paper folding activities are used to demonstrate how mathematical modelling and technology can support mathematics learning.