This was a song on Sesame Street back in the late 1960's. Sometime between then and the 1990's someone decided that this was not a good educational activity and Sesame Street discontinued it. When I sing it to today's teenagers they look at me funny.
(You can see a Sesame Street clip of that activity here.)
It tends to come up when I am coaching someone for the ACT English section. The correct answer is frequently the "odd man out" - the one choice of the four that is grammatically different from the other three.
For example, in one question from The REAL ACT Prep Guide the answer choices were:
a. NO CHANGE (it was written as "straighten it" in the passage)
b. straightened them
c. straightened those
d. straighten them
Choice "a" is the only one in which the pronoun is singular instead of plural, and choice "a" was, in fact, the correct answer.
I have noticed a number of trends about the frequency of correct answer choices on this section of the ACT, so I recently did an experiment. I completed an ACT English section without reading the passages. Instead I chose an answer based on a number of rules. One of the rules was that if there were an identifiable "odd man out" I would choose it. For each question I wrote my answer choice and then next to it the rule I had used to choose my answer. I used the "odd man out" rule 20 times. The choice was correct 11 times, or 55% of the time.
I know that the anti-test campaigners are routinely horrified by test strategies that allow one to answer a question without even reading the material, but I would like to point out that this particular strategy does require a knowledge of grammar. One must recognize that one of the choices is different in a particular way.
I am rarely asked to coach for the ACT (the SAT is a bigger deal in my state,) but I will continue to put considerable emphasis on recognizing when "one of these things is not like the others."