This study aimed to determine how preschool teachers handle mathematics learning processes in their mathematics activity plans and which contents they include. The study used the document analysis method as a descriptive research model. The study examined 200 mathematics activity plans applied by 10 preschool teachers working in preschool education institutions in the 2020-2021 Fall and Spring academic terms. The data of the study were collected with the Mathematics Activities Assessment List (AEL), which the researchers developed. The researchers analysed the data obtained in the study separately by using the coding system without specifying the teachers' names for confidentiality. As a result, the researchers determined that preschool teachers planned mathematics activities mainly in large group activities and integrated them into their activity plans. On the other hand, they also found that teachers included concepts such as number/counting and quantity more in their mathematics activity plans and they planned mathematics activity plans as classroom activity plans. In addition, they included family participation activities in mathematics activity plans.