Freerice is owned by and supports the World Food Programme. For every correct answer 10 grains of rice are donated through the World Food Programme. Users can answer questions in several categories including two on Maths, one on multiplication and one on basic Maths. It is possible to play at various levels, so choosing level 10 for example means that questions on fractions and directed numbers will be included. Students can sign up (under 14s need parents permission) or login easily with their Facebook account to track their totals and join and create groups.
Well Good Water Aid aims to raise funds for wells to supply water to the developing world. Well Good has questions just on Number as shown in the image here. A good way for younger students to practise their skills with Negative Numbers!