Teachers around the country are engaging in "CFAs" which are Common Formative Assessments (as if you didn't already know the acronym). We all know what assessments are and the fact that they are common has been happening for years. The piece that is fairly new, to some extent, is the idea of quickly turning around the data and informing instruction. This is where classroom polling comes into play using a site like Poll Everywhere where students can use their mobile devices to quickly inform you of what they know and more importantly...what they don't know using text messaging or by voting through a website. The data can then be shared directly on the web. It is very simple to setup and you don't even need an account.
Poll Everywhere can be used simply to allow students to demonstrate if they are with you during a lesson or you can have students text in their questions about a homework assignment which can then jump start the next day's lesson. Check out this video for a more detailed overview of the service.