Since their launch in 2020, LEGO SPIKE Prime robots have become regular and popular participants in robotics activities and robot competitions. Accuracy and consistency are very important factors in the control of mobile robots, but the precise execution of a single movement is often a challenge for participants in robotics activities. This is particularly true in curved movements. The blocks used to program LEGO robots do not provide enough information to accurately plan turning motion in advance, so the trial and error method is often used. This paper proposes a more advanced method to explore the relationship between steering parameters and turning radii. As a result of a series of experiments, an approximate function relationship is presented that gives the steering parameter required to achieve the desired turning radius. Recognising the limitations of the steering parameter, we also developed a formula and method that can give the turning radius using the ratio of wheel speeds.