Problem-solving skills and understanding of domain, knowledge (e.g., fighting misconceptions) are important goals in both secondary and tertiary science education. A prototype of an instructional task is presented which aims at improved problem-solving skills based on understanding of domain knowledge. In this task, comparing carefully selected solved problems by groups of students is utilised as a learning activity for the acquisition of adequate problem schemata. The task is designed as a part of the so-called UBP-program (UBP=Understanding Based Problem solving) currently being developed, for education in science. The result of an evaluative study for the field of mechanics is presented. The UBP-task appears apt to improve problem-solving skills at a less advanced level of physics education (e.g., 10th grade), especially for students normally performing poorly—who are often girls.