The choice between everyday and every day depends on how it is being used. Use everyday when it is an adjective and every day when it is an adverb.
Sometimes it can be hard to tell the difference between an adjective and an adverb. Remember that an adjective describes a noun, and an adverb describes a verb, an adjective, or another adverb.
When everyday is an adjective it means "used or seen daily" or "ordinary." You can tell it is an adjective because it always comes before the noun it describes. Below are some examples of how the adjective everyday is used:
When you use the adverb phrase every day it means "daily," "day by day," or "every weekday." One way to find out if you need to use the two-word form is to see if you can put another word (an adjective) between "every" and "day" as in "every single day." Below are some examples of how the adverb phrase every day is used:
So then the sentence you should use is "I go to school every day."
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