"Awhile" vs. "A While"
"A while" is a time, a noun. The article "a" before "while" is a sure sign that you're dealing with a noun. Notice in the following sentence that you could replace "a while" with another article-noun combination such as "a year":
It's been a while since Squiggly tried marmite.
"Awhile" means "for a time" and it's an adverb. Notice in the following sentence that you could replace "awhile" with another adverb such as "quietly":
Go play awhile.
Finally, just to make it confusing, if you rephrase the previous sentence and replace the adverb with a prepositional phrase, you need the noun again because an adverb can't be the object of the preposition.
Go play for a while.
