The following article from eduTOPIA lists five formative assessment tools that you may want to explore http://goo.gl/ZoCSzo .
Two of the tools mentioned, Socrative and Kahoot, are tools that TLT have conducted session on in the past and have created step by step tutorials for which can be found at http://blogs.cofc.edu/tlttutorials/
Another tool mentioned, Plickers, is a tool that TLT has featured at our past FTI and will be featuring again at our upcoming Teaching Learning and Technology conference. You will have a chance to explore Plickers and hear from an Instructor about their experience using it in the classroom by attending the Faculty Discovery Lab and Lunch on 3/9. You must register for the Conference AND for this Lab and Lunch. Register at: https://goo.gl/4IoQJc