The use of tablets in preschool has increased during the last years. Not everyone is positiveabout young children in preschool, using a technological tool already in at such an early age. Inthis bachelor thesis within the science area of informatics, the researchers research about whateffects the use of tablets in preschool has on children's mathematical knowledge.The result shows the effects on children's mathematical knowledge when using tablets inpreschool. The effects may depend on how the tablet is used in education and also if the use ofthe tablet is guided or not by a preschool teacher. How the tablets are used appears different invarious departments. Some departments in preschool use the tablet more and others less.Preschool teachers want to develop the use of tablets since they see the tablets as an educationaltool.