Easy to use tool for creating flipped classroom lessons. Use the built-in search tool to find videos, images, or social media posts, put them into a timeline, add text and/or polls, and share. Free account has very limited media storage, but not an issue if you only use embedded media. Paid service has educator discount and is only $2.50/month.
Useful tool lets you upload PowerPoint or Keynote presentations and then share as a link. You can then insert polls or questions and get real-time feedback from students/viewers.