SSDD stands for Same Surface, Different Depth. They are a special set of problems that may look the same at first glance, but require different mathematical ideas to solve them.

SSDD Problems have become one of my key strategies to use with my students to help them become better problem solvers.

You can search for different topics using the tags on the right-hand side (or below if using a mobile device), and you can find out more about SSDD Problems on this page.

My 2020 book, Reflect, Expect, Check, Explain: Sequences and behaviour to enable mathematical thinking in the classroom, goes into detail about making the most of these activities in the classroom. You can order the book from Amazon, John Catt, or wherever you get your books.

My 2023 book, Tips for Teachers: 400+ ideas to improve your teaching, details my most recent thoughts on using SSDD Problems effectively. You can order the book from Amazon, John Catt, or wherever you get your books.

I have an online course store which offers low-cost, high-quality CPD on-demand. Each course contains short videos, resources, research, activities and questions to reflect upon. The courses most suited to the questions on the SSDD Problems website are:

• The four ingredients of problem solving
• Student practice