The development and evaluation of a computer package for teaching mathematics to 6‐7‐year‐old pupils is presented. The package consists of six computer programs followed by worksheets and teaching guides and covers basic mathematical concepts met in the school curriculum. It aims to enhance children's understanding of certain concepts and structures, help them to develop and communicate problem‐solving strategies, stimulate interest and provide a variety of learning environments. The programs mainly present one teaching point and vary from rather structured ones to ‘open’ mathematical explorations. The context has been chosen to be familiar to the children and a variety of representation models has been adopted to facilitate children's understanding. The evaluation is designed to determine the effectiveness of software in terms of the aims stated at the design stage. The programs were used by children moved from their classroom, by a class of 30 children working in groups of three in the computer room and in their normal classroom. Methods used were observation and interviews with children and teacher, whole‐class discussion, and analysis of children's written work. In general, the developed software appeared to fulfil its main goals. It encouraged discussion, problem posing, mathematical explorations that led the children to reflect on their methods and conceptions and develop them.