This paper presents a series of illustrative LEGO Mindstorms-based science and math activities, developed under an NSF GK-12 Fellows project, for elementary, middle, and high school grades. The activities, developed by engineering and science graduate Fellows in partnership with K-12 teachers, are grade appropriate, address pertinent learning objectives, and adhere to the science and math learning standards of New York City and State. To measure the effectiveness of the use of LEGO Mindstorms-based lab activities in science and math lessons, pre- and post-lesson assessment surveys, consisting of content and evaluation questions, were administered to all participating students. In this paper, we provide: our motivation to investigate the effectiveness of LEGO Mindstorms-based lessons; descriptions of six LEGO Mindstorms-based science and math activities and their associated assessment; statistical analysis; reflection on the effectiveness of the lessons; and recommendations for future work.