STEM has an extraordinarily strong role to play in schools. STEM underpins every part of our lives, its everywhere in the world around us. With STEM in mind, the emphasis should be based on skills such as questioning and problem solving which can lead to better creativity and greater innovations. It builds resilience and boosts confidence, and it enables children to embrace their mistakes as part of the learning process. It also encourages many other factors such as experimentation, tech-use and teamwork.
One website I have used quite often is http://www.sciencebuddies.org/stem-activities. It has loads of fun, hands on STEM activities, challenges and demonstrations for kids. Most materials are easy to find and most activities take no time at all. Some of the experiments include build a balloon car, build a paper rocket, elephant toothpaste, walking water, build a sandcastle that can support a brick, can you catch a bubble, turn milk into plastic, make a miniature water cycle model and many more.