Okay, imagine the Cookie Monster singing his 'One of these things is not like the other,' song. Kids quiet down immediately. You don't even have to say a word... just point at the screen. You can dance to the music. Hands will pop into the air. Resist. Don't call on a student until the song ends and many hands are in the air.
The first kid will have an answer. Resist commenting. Ask why they think that (they may have an entirely different answer than expected, but their scientific explanation could be right). Listen. Hear them out. Say, 'Hmmmm'. Call on another student.. Ask why and listen. I usually call on three or four. I tell them what my choice would have been and clear up any misconceptions. It takes 5-7 minutes and the discussion is priceless.
I use ONE slide everyday. This slideshow includes 20 slides (some slides are diagrams and some are words). Concepts are fifth grade concepts and are aligned with the Texas TEKS.
I am not able to include the Cookie Monster song, but you can find it on web. KIDS LOVE IT!!!