In the study, it was aimed to determine the students' basic mathematical problem-solving skills according to the problem-solving stages of Polya and the effectiveness of preschool education in problem solving. Besides, in the study, it was specified that the problem posing skill levels of the students were determined according to the definition made by Stoyanova and Ellerton. The study group of the research consists of students who had to take a break from pre-school education for a while due to the COVID-19 pandemic that emerged at the beginning of 2020 in Turkey, and who completed the second education-teaching period remotely and started the first grade in primary school. Descriptive scanning and clinical interview methods were used to determine problem solving and setting approaches. Within the scope of the study, the answers given to ten different basic problem types to determine the basic mathematical concepts and skills that children should acquire for mathematical development in early childhood and the problems which they posed like these problems were analysed. In addition, the opinions of three classroom teachers related to the subject were presented. According to the results obtained, the performance of the students who started the 1st grade during the pandemic period was determined to be low in the stages of problem solving, understanding the problem, preparing a plan, implementing the plan, and evaluating it. The most successful problem type of the students was the separation problem and the most difficult one was the division problem in the form of sharing equally due to incomplete concept knowledge. It has also been observed that students who have difficulty in understanding long and multi-stage problems cannot pose similar problems to problems they do not understand. The number of problems posed for the semistructured problem posing situation was high. Interviewed teachers stated that students who started primary school during the pandemic were more anxious and shyer. Teachers made suggestions in the context of families to increase family participation in mathematics education and make the lessons more efficient.