This study aims to analyze elementary school six graders’rates of correct answers and difficulties in solving problems by suggesting 5 typical mathematical problems from school science. Besides, this study analyzed the process of their solving problems by Hogan’s Mathematical Structure. The research results can be summarized as below. The rate of correct answers to problems about average was highest out of all the problems about weight, average, pressure & volume, the length of days and speed, while the rate of correct answers to problems about weight was lowest. However, elementary school students responded that the problems they actually found most difficulty were about pressure & volume. Their difficulties in solving mathematical problems from school science were commonly in the context of learning transfer that they should use their mathematical knowledge for school science. As a result of analyzing the process of elementary school students’ solving problems by Hogan’s Mathematical Structure, this study discovered that they made mathematical knowledge errors most, but there were only 5 students who made errors of strategic knowledge, which indicates an ability to solve problems by properly applying particular mathematical knowledge and scientific knowledge together. The main reason why they had such difficulties seemed to be because they hardly had chances to apply their mathematical knowledge to science due to their errors of mathematical knowledge