Different by one

This is another nice investigation from Nrich, it explores factors using Cuisenaire rods in an interactive environment so you would need for students to have access to computers. The teacher’s notes are helpful but the solutions are particularly good here for seeing how you could encourage students to work on this. Depending on the ability of the class they could solve this using algebra, if they are low ability they can just work systematically to find solutions and then try to explain their answers in terms of factors. Thank you for sharing.