I was recently talking with a teacher about the common formative assessments her department uses to gage learning in the classroom. Most teachers, she told me are using paper based methods. That can be a very effective way to find out what the students are understanding from your lesson. They come in a variety of forms including bellwork and exit tickets. Unfortunately, these assessments are often hard to grade just because there is so much physical paper to sort through and record. After all, teachers are notoriously stretched for time and energy.
An alternative to using paper would be to use a clicker system or other electronic data collection tool. Clicker technology has been around for quite some time and includes systems such as Promethean and CPS. Both of these products are great by themselves. However, you need to be careful not to have both programs on your computer at the same time. They don't play well together.
Some other methods of electronic assessment involve the internet. Free online testing websites have exploded over the past 6 months as institutions such as Blackboard, Pearson and Google have invested in what is known as open course technology. The idea is that companies stand to gain big bucks if you use the free testing material, since you'll be more likely to buy their other products.
My favorite (free) online testing sites are:
Google forms (part of Google docs)