This feature focuses on using those tasks which most children can access, because the mathematical content is relatively simple, yet which offer opportunities for children to extend their thinking and reasoning skills through the choices they make.

LTHC was a feature several years ago and so we thought it was about time to update it, particularly in line with the new mathematics National Curriculum (DfE, 2013). We have reflected on what it means to call a task LTHC as well as adding some new thinking to this feature.

This article explores what LTHC tasks are and why they are a firm favourite here at NRICH. We recommend that you start by reading the article to understand what makes a task LTHC and then delve into some of the activities we have selected.

Sort the houses in my street into different groups. Can you do it in any other ways?

The computer has made a rectangle and will tell you the number of spots it uses in total. Can you find out where the rectangle is?

Noah saw 12 legs walk by into the Ark. How many creatures did he see?

Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?

Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?

Place this "worm" on the 100 square and find the total of the four squares it covers. Keeping its head in the same place, what other totals can you make?