proposition, preposition

Proposition or proposition means an offer or suggestion, or a plan or scheme--
He explained the proposition to the committee, and they agreed to consider it.
His proposition seems more reasonable than the others.

Proposition also means a formal statement on a subject brought up for discussion or debate--
"...and dedicated to the proposition that all men are created equal."
We are going to discuss the proposition that men and women should be equals.

Preposition or preposition is a part of speech ( kind of word ) that shows the relationship between the subject ( actor ) of a sentence and the object ( acted upon )--
In the sentence "I am going to the store", "to" is the preposition.
Each one of these is a preposition: with, to, from, over, under, on, up, down, and out.
A preposition may also show time, distance, or location, as in: "I have to go to work at 9."
 
Now that you know that, you can say--
"The proposition to have the students memorize each preposition was voted down."