The way to pronounce "often" is not "Of-TEN," but it is actually "of-fen".

Just think of "listen".

Do you pronouce it: "Lis-Ten?"
Then don't say "Of-Ten."

Many people pronounce the word often, "of-TEN" but they are wrong. 

The "t" is silent.

Just like "hasten," "soften," "moisten," or "glisten," you don't say the "t." 

Parts of Speech: What is a preposition?

A preposition shows the interacting relationship between ideas.

Think of a bunch of clouds.  What interacting relationship can they have with a bird?

The bird flew through the clouds.
The bird flew under the clouds.
The bird flew around the clouds.
The bird flew between the clouds.
The bird flew over the clouds.
The bird flew beyond the clouds.
The bird flew among the clouds.
The bird flew into the clouds.

The highlighted words are prepositions.  The highlighted word plus "the clouds" is the prepositional phrase.

Here's a list of other prepositions: http://www.englishclub.com/grammar/prepositions-list.htm

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