The word lose, with one o, is a verb that means you have lost something that belongs to you. It can also mean to reduce or lessen.
My little sister always loses her toys.
Vitamins lose their potency when they are left out on the table.
Spelling Hint 1: When you say the word lose aloud, you pronounce the s like a z.
Spelling Hint 2: Think about the words lose and lost. Both words have the same meaning (when you lose something, it's lost), and both are spelled with only one o.
The word loose, with two o's, means that something is not tight, or that it's coming apart.
He loosened the reins on his horse.
My shoelaces always come loose during gym class.
Spelling Hint 1: Unlike lose, the word loose is pronounced the way it looks, with the s making a regular s sound.
Spelling Hint 2: Remember the phrase loose as a goose. Both loose and goose are spelled with two o's.
More Helpful Hints
Note that these two words can fulfill different grammatical roles. The verb lose can be turned into a noun by adding a different ending (you'll see which one as you complete the exercise below, but we don't want to give away any answers here!). The word loose can be used as a verb, an adjective, or even an adverb, depending on the ending you choose.
The words lose and loose are used in many idiomatic expressions (that's a fancy term for slang). This basically means that their conventional definitions can be stretched a bit, so you may have to think outside the box for a few of the questions below.