This is an activity that I use frequently with my Spanish students to supplement what we are learning in the textbook. It gives the students valuable conjugation practice and it keeps them busy and focused for the duration of the class!
You can choose whichever lessons you are needing to practice (see website), insert them into the worksheet, and then let the students loose to do the work on the computer. I tell them it's "OK" if they don't get all the way finished, and to go as far as they are able. I purposefully add more exercises than they can complete in the hour -- to make sure they have plenty to do.
This also makes a GREAT substitute teacher lesson plan!!! It's self-explanatory, the kids stay busy, and the substitute only needs to monitor to be sure the students are staying focused (and not on websites that do not pertain to the lesson).
Simply download, print, and choose the lessons you wish to cover! Enjoy!!