Mathematics is of major importance in science subjects. Unfortunately, students struggle with applying mathematics in science subjects, especially physics. In this qualitative study we demonstrate that transfer of algebraic skills from mathematics in physics class can be improved by using pre-knowledge effectively. We designed shift-problems involving instructional models to carry out small interventions in textbook problems. Shift-problems are feasible for teachers to adopt in teaching practice. To gain insight in the extent to which students improved their application of algebraic skills including basic skills and symbol sense behaviour, we selected three grade-10 physics students. In round one, the students solved algebraic physics problems as they appear in physics textbooks. Two weeks later in round two, the same problems were presented as shift problems to them where we activated prior mathematical knowledge by providing systematic rule-based algebraic hints at the start of these tasks. Algebraic skills were presented in a similar way to how these were learned in mathematics textbooks. We observed that students' problem-solving abilities increased from 48.5 % in the first to 81.8 % in the second round, indicating the effectiveness of how we implemented shift-problems. Furthermore, we discussed the implications of our results for the international science audience.