Science teaching is based upon the programmes of study in the National Curriculum. Lessons are delivered in a variety of ways ranging from formal whole class demonstrations to small group investigations. Children are encouraged to observe, question and reason systematically and logically. At Key Stage 1 Science is usually taught within the topic being studied at the time. At Key Stage 2 science may sometimes be taught more formally as a separate subject in order to ensure that all the aspects of the programme of study are thoroughly covered.