Novel technology has been applied to improve students' learning abilities in different disciplines. The research in this field is still finding suitable methodologies, tools, and evaluation mechanisms to devise learning frameworks with high impact on students' performance. This article describes an instructional method to perform Newtonian physics experiments by programming a mobile robot. Such experiments allow the learners to design, implement and visualize physics concepts, thus using the robot as a "cognitive tool" or "mindtool." An accurate assessment of the students learning gain, involving 29 high-school students, shows that the proposed method provided significant improvements in the students understanding of the first Newton's law, the second Newton law and the superposition principle. The learning gain has been measured through the Force Concept Inventory questionnaire. From this study, we can state that programming a mobile robot to perform physics experiments can improve knowledge about Newtonian physics, even without giving specific lectures in the subject and with a much shorter lecture plan with respect to traditional lectures.