I use this at the beginning of each year with each student to let me know what he/she knows already. It checks letters, counting, numbers to 20, shapes, colors, rhyming, letter sounds, and a handful of sight words.
I only include a few sight words because most of my students don't know sight words and would be frustrated with a whole list of words. This gives me a clue as to which students may be readers.
I can use this to go back and check to see how each student has progressed. I just use another color pen/pencil and write the date at the top or I print out another copy to check in again.