STEM education is a pedagogical philosophy which aims to draw the interrelationship between science, technology, engineering and mathematics to solve complex problems in real life situations. In order to use STEM education to foster students' learning, the researchers designed STEM activities for middle school students related to the concept of force and motion in three different approaches: a linear model, a jigsaw learning and a stand-alone engineering design activity. To compare the effectiveness of the three approaches, the researchers analysed students' reasoning and problem-solving scores gained before and after doing the activities. The result showed students participating in the linear model and in the jigsaw learning significantly outperformed those in the stand-alone engineering design activity. In addition, when comparing conceptual development between those attending the linear model and jigsaw learning, the result showed that the former significantly outperformed the latter. It is therefore suggested that to maximise the effectiveness of STEM activities in promoting conceptual understanding as well as reasoning and problem-solving skills, teachers should adopt the linear model. However, when instructional time is limited, the jigsaw learning can be considered as an alternative approach. The stand-alone engineering design activity although can promote students' enthusiasm to learn, it may not sufficiently lead to the development of reasoning and problem-solving skills as expected.