Physically active learning is considered to enhance learning and additionally addresses health goals like increasing activity levels and reducing obesity. However, physically active learning has rarely been applied to science and engineering learning, or utilized with younger learners (e.g under sevens). This article describes a physically active learning approach to introducing one area of science and engineering, trialed with children from age 3 upwards. Specifically, the game bacteria-tag was designed to start discussions around bacteria and diseases and medicine selection, which can be extended in various ways, e.g. to introduce ideas around antimicrobial resistance, bacteria structure etc. Additionally, the game helps to highlight the role of bioengineers in society, helping to broaden perceptions around engineering, which is especially useful at a young age where misconceptions can lead to lack of interest and career rejection. Bacteria-tag has been successfully utilized in a range of schools and nurseries (PreK to 5th grade), proving effective at engaging children and inspiring learning.