Simple to use web tool for doing quick checks for understanding.
Teachers can set up a free account on understoodit.com and get a custom URL to share with their students. Loading this web page presents students with big "Understood" and "Confused" buttons. Clicking these buttons instantly updates the bar and line graphs on the same page so you can see where the class is in terms of comprehansion.
The teacher can set the amount of time before a new click is accepted.
*Note: Students will need a device to record their understanding.