This worksheet is designed to help students practice simplifying and using imaginary numbers. I recently used this with my Algebra 2 class, and it went very well. There are a variety of problems - simplifying negative radicals, multiplying radicals (some negative), simplifying "I" to a power, and multiplying imaginary numbers. There are also some basic equations with imaginary answers. The scrambled answers are helpful for students as they go through the worksheet to make sure they are doing the problems correctly. Having students check their own solutions frees me up to go around and tutor students.
One suggestion that I have is to drill into students two things: "I" is the square root of -1 (and vice-verse), and the most important thing is that "I" squared equals -1. If they can remember to turn "I" squared to -1, it helps tremendously.