Why is the statement ......"I is a student" not correct but "I am a student" correct?

Does this have something to do with the 8 forms of Be? If so, where can I learn more about when to use the 8 forms of Be. Thank you. - Mandie
"I is" is incorrect and "I am" is correct AXIOMATICALLY. That is - it's a rule you have to learn, not a consequence.

Where can you learn more? Right here...
I am
You are
He is
She is
One is
It is
We are
They are

No-one is
Nobody is
Nothing is
Someone is
Something is
Anybody is
Anything is
Everybody is
Everything is

If any other word or phrase precedes is/are then you should use "is" if the word or phrase is singular, or "are" if the word or phrase is plural. For example "This website is ...", or "The people on this forum are ..."

Hope that helps,
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The exception is a non-count noun such as water, cake, bread, etc. These nouns are always treated as singular i.e. "water is refreshing", "cake is delicious", "bread is made by bakers".
That's not an exception. Nouns which are being used as non-count nouns, by definition, can never be plural.

But - as I'm sure most of us realize - a noun can be count or non-count DEPENDING ON HOW IT IS USED.

"That cake IS delicious" = correct - count noun, singular
"Those cakes ARE delicious" = correct - count noun, plural
"Cake IS delicious" = correct - mass noun