**What is an arithmagon?**

Clearly, the numbers in the rectangles are the sum of the numbers in the adjacent circles. Of course, there is no need to use addition and no need to use triangular arithmagons!

These could be used with students of all ages. Young children could practice basic skills or students studying advanced Mathematics could look at Calculus or Complex Numbers for example.The challenge is, of course, to go backwards…(**Going backwards in Mathematics** really helps understanding).

Colin Foster has written a suggested **lesson plan on Arithmagons** with full commentary.

Nrich has some very useful resources including **this introduction **to arithmagons which includes an interactive allowing numbers to be changed and would work well on an interactive whiteboard. See also these further Nrich resources – **this on multiplication **and for older students a rather more **advanced multiplication arithmagon using complex numbers**. Also on Nrich, **Irrational Arithmagons**.

From Mark McCourt’s **emaths**, the Teacher Resources include **Investigations, Rich Tasks and Puzzles**; these include a small collection of Arithmagons by Alan Hodson covering Number and Algebra. The Algebra resources include simplification using like terms and solving linear equations. A PowerPoint file showing an investigative approach using number and algebra and notes are included as is a useful sheet of 15 blank Arithmagons for students to record answers.

From Don Steward, try his **Expressions Arithmagons**. Note the very efficient use of space here! Also from Don Steward, have a look at **Directed Number Arithmagons**.

For ideas to use with older students see **Jonny Griffiths RISPs**; **RISP21** is on ‘Advanced Arithmagons’ (if you **choose RISPs organised by **topic, you will see RISP21 Advanced Arithmagons under Basic Algebra).

Jonny Griffiths RISPS have been mentioned before – see the **Rich Tasks resources** for Older Students. Another site included in the Rich Tasks resources is the** New Zealand Maths problem solving site**; a resource on that site uses arithmagons to **form and solve linear and simple quadratic equations.**

Noting this tweet from Spencer Riley (I really like his **TeacherLED** site which has free high-quality teaching and learning resources compatible with desktop and mobile devices.) I had a look at his Arithmagons resource and can verify it worked very well on my phone as well as on the desktop.

From Craig Barton, we have a **complete collection**, covering Number, Algebra and Shape and Space. Each resource includes a PowerPoint File with clear instructions and a selection of challenges to really make your students think.

From Jonathan Payne, try this **Arithmagon Generator**. This is very simple to use and would be an ideal lesson starter. I like the option to use fractions, also to mix the question types as you see in the image. It is possible to choose missing sides, mixed or missing vertices.

One of the many free resources (**do a search on ‘free’**) on the excellent **MathsPad** is this interactive – **Negative Arithmagons**. (MathsPad is a subscription site, but very low cost and good value for schools – **see details**).

On **Transum Mathematics **(home of the excellent Starter a Day), the **Arithmagon activity** has options for forwards and backwards problems on Addition, Multiplication and Subtraction at various levels.