"Within YouTube there is a free tool for creating audio slideshows. You supply the images and YouTube supplies the audio track. You can pick from thousands of audio tracks to match to your slides. After adding your slides and selecting an audio track you can add speech bubbles to your slides. I demonstrate all of these steps in the video embedded below."
Typito is a good tool for creating simple videos. Typito is designed for making audio slideshows like those you might have made in the old YouTube photo slideshow tool or with Animoto. Typito offers a bit more control over the editing process than Animoto does.
HHMI's BioInteractive is a good place for science teachers to search for science lesson plans, videos, animations, and slideshows to use with students. You can search the BioInteractive library according to topic, keyword, or resource type.
Photo slideshow, slow-motion videos, create linked series of videos, blurring faces in videos, adding color/light filters, add captions, add music, hide the video from public