The aim of this research was to examine the skills of prospective teachers to design mathematics connection activities with different disciplines. In the research it was asked that prospective teachers design a mathematical activity in which mathematics was connected with the ability to connect to different disciplines. For this purpose, the research was carried out using the case study model. The study group had 19 mathematics, 11 physics, and 10 chemistry prospective teachers. The designed activities were examined according to purpose, cognitive processes and mathematical competence and skills. As a result of the analysis of the obtained data, the concept of ratio-proportion was mostly mentioned in the designed mathematical learning activities. It was involved also in other mathematical concepts such as derivative, function, proposition and percentage. In the classification of the designed activities according to the aims, it was found that the consolidation activities were the most and the difficulties and the misconceptions activities were the least. The 5 groups of prospective teachers preferred to develop activities for new learning. When the activities designed by prospective teachers were classified according to the cognitive processes, they were designed to practice, evaluate, consider, apply and produce in descending order. The activities that were developed did not include interpret and create activities. According to mathematical competence and skills, problem solving, modeling and different representations activities were mostly involved. Activities for generalization, proof and reasoning and technology use were the least developed activities.