This study aims to improve students' conceptual understanding and problem solving through the application of problem posing learning based on the hot potatoes application based on the problems of the fifth semester students of SDK Maria Fatima Bangkalan. This study uses a quantitative approach. Quantitative research is carried out by describing the data in the form of numbers, namely to determine whether there are any consequences of problem posing learning based on the hot potatoes application on concept understanding and problem solving. The subjects of this study were fifth grade students of Maria Fatima Catholic Elementary School, Bangkalan, Academic Year 2019 - 2020 with flat-building material. The results showed: (1) The effect of problem posing learning based on the hot potatoes application on students' understanding of mathematical concepts was higher with an average value of 85.83 than the control class. (2) The effect of problem posing learning based on hot potatoes application on problem solving has a higher average value than the control class, namely 88.68. (3) The effect of problem posing learning based on hot potatoes application can improve concept understanding and problem solving. Based on the results of data analysis, it can be concluded that problem posing learning based on hot potatoes application can improve the conceptual understanding and problem solving of elementary school students, but still requires adjustment to the situation and conditions at school

Keywords : Problem Posing Learning, Hot Potatoes Application, Concept Understanding, Problem Solving