“I know what I mean but I can’t ‘splain it.” I used to hear that from my middle school students in physical science, especially on essay questions. Sometimes the concepts are indeed hard to ‘splain in words. Visuals and observations of real events can make the concepts more real for students.

For example, a recent NPR blog Cinderella’s Ball, This Time With Pendulums had a video of a set of 15 pendulums, each a different length. When released simultaneously, watch what happens as a camera placed on the side of the apparatus captures the motion. What’s happening here? Hmm. I wondered what it would look like from the front. And sure enough, there was a blog comment with the same question and a response with a link to a video of a slightly different setup but with the camera in a different position. I checked out the creator of the video, Harvard Natural Sciences Lecture Demonstrations.  The site has resources for teaching concepts in physics and mathematics, but I spent the most time looking at the videos. These are short and to the point—great discussion starters or bellringers too.
Concepts in chemistry can be hard to understand, too. Middle School Chemistry from the American Chemical Society can be helpful. This series of lesson plans uses the 5E framework for lessons on matter, changes of state, density, periodic table/bonding, the water molecule, and chemical changes. The lessons include hands-on activities, simulations and animations, and student handouts.