Measurement in geometry is one of the key areas of school mathematics, however, pupils make serious mistakes when solving problems involving measurement and hold misconceptions. This article focuses on the possible links between lower secondary pupils' (n = 870) success in solving non-measurement tasks and calculations tasks on area and volume and on their problems when solving measurement tasks. The study uses a mixed research design. Statistical methods are used to find correlations between the two types of tasks and a qualitative analysis is carried out to identify mistakes and misconceptions. The results show that there are indeed relatively strong links between success in non-measurement tasks and calculation tasks, and consequently, when teaching, attention must be paid to the development of both types of skills. The study identified pupils' mistakes in tasks which are within the Czech curriculum but which proved to be difficult, such as a missing link between algebraic and geometric representations, a tendency to linearize and/or to employ pseudo-analytical thinking. The study identified differences between individual classes which point to the significant role of the teacher and/or influence of the textbook used.