What research has shown about teaching STEM to early learners is that they are perfectly adapted to learn STEM concepts, and it is not difficult to teach STEM to young children. What must be done is that teachers must find a way to tap into their natural and innate curiosity about the living world. Once we simply allow children to investigate, encourage them to ask questions about the world around them, you are engaging children in STEM.
There are quite a few recommendations on how to teach STEM, none is more simple and more powerful than this: take children outside into nature. It is, I believe, abundantly apparent to almost any adult that once you let a child walk down a dirt path in the garden they start to explore their surroundings immediately. It is that sense of explorer that we need to tap into. Ask questions of your little researcher, encourage more exploration, and provide more opportunities to return to these types of settings. If you don’t have access to natural areas or even a more developed park, you can plant a small garden, make a terrarium, or simply make a start by growing seeds in cups.