I think we are moving away from the teacher being the one with all of the knowledge and all of the answers. Our students are more than capable of doing a lot of the WORK, so why not let them do it? When we finish a STEM Challenge, I ask the students to go to work on our Google Chromebooks to find the science behind the challenge and you know what...they kinda surprise me every time by doing such a great job!
Here is the sheet that we use to record our research. It is pretty easy to follow and we usually hang them up with our STEM Challenge data sheets (another part of the challenge that the kids design and create themselves).
Why not let your students do some of the work by finding the science behind the STEM challenge? We share our results and then defend them as necessary with evidence. The kids are immediately engaged and they retain the concepts much easier than if I just explained the science to them after the lesson.