We did a few things. First we bought an entire box of these small toads, it was about 4ft by 4ft and 3ft deep. We cut a hole in the bottom and and wrote do not pick up all over it, then placed it in the main entry of our school. Kids start arriving around 7, janitor is called to remove box around 715, box is lifted, and toads go everywhere. They spent the whole day catching all these, it was great.
We also actually used the chicken idea and got 4 little pigs and marked them as 1,3,4. Then they were greased and since there are 4 entry's into our cafe, we set each of them out of a doorway, just to make sure they believed there was a 4th. good time