This study will test whether a short training program - designed to improve memory and attention skills - will benefit mathematical reasoning in preschoolers from a range of socio-economic backgrounds. The investigators will test how long any benefits last for and whether any intervention effects are greater for children from disadvantaged backgrounds. The aim is to test interventions that aim to close the achievement gap by improving skills known to underpin academic skills, at an age children may benefit most from training.

Children's academic success across a range of domains is related to their executive function skills - specifically by their ability to maintain and update information (working memory) and to suppress inappropriate responses (inhibitory control). These skills undergo significant development during the preschool years. Notably, preschool executive function skills strongly predict school readiness, as well as concurrent and later academic achievements in mathematics. The aim of this project is to test an intervention that is specifically designed to improve preschoolers' executive functions - crucially, before the achievement gap sets in. The study will be carried out, following CONSORT (2010) guidelines, with typically developing preschoolers (aged approximately 4 years of age). The study will include children from socioeconomically advantaged and disadvantaged families. Children will be randomly assigned to either an executive function training group or an active control group. A nominated person external to the project will conduct the random allocation process. The random allocation will be done for each nursery to ensure roughly even numbers in each group from each nursery. Children in both groups will complete computerized tasks lasting 15-20 minutes once a week for four weeks. The investigators will compare the trained children to an active control group that closely matches the training in terms of activity. To check for improvements, the investigators will measure cognitive and maths skills at baseline (one week before training); one week post-training; three months post-training; and one year post-training. These assessments will be conducted by testers blind to the child's group.

Inclusion criteria:

• Must be attending a nursery school attached to a primary school.
• Must speak and understand English (class teachers will advise on this).
• Must have at least one measure of working memory completed at baseline and one measure of inhibitory control completed at baseline.

Exclusion criteria:

• Must not have a significant diagnosed or known physical, mental or learning disability.