Throughout a child's education, there is a strong emphasis on enabling children to use language to work together effectively. Cooperative learning has been widely credited for having positive impacts on every child's education, whatever their 'ability'. You can read more on this by clicking here.
One reason for these developments is that recent research has shown the importance of the link between spoken language, learning and cognitive development (e.g. Mercer, Wegerif & Dawes, 1999; Mercer, Dawes, Wegerif & Sams, 2004*).
Through using language and hearing how others use it, children become able to describe the world, make sense of life's experiences and get things done. They learn to use language as a tool for thinking, collectively and alone. However, children will not learn how to make the best use of language as a tool for communicating and thinking without guidance from their teachers. School may provide the only opportunity many children have for acquiring some extremely important speaking, listening and thinking skills.
On a daily basis, sometimes without even realising it, you are helping to develop your child's speech and therefore improve their cognitive capabilites. To see how you could further help your child, take a look here at a short article by the much-loved children's novelist and poet, Michael Rosen.
*Mercer, N., Dawes, L., Wegerif, R., & Sams, C. (2004). Reasoning as a scientist: ways of helping children to use language to learn science. British Educational Research Journal, 30, 3, 367-385.