Learn Swedish: Jag kontrollerar schemat varje morgon. - I check the schedule every morning.

Just like in English, the word varje (every) is always followed by a noun in its indefinite singular form. You say varje morgon (every morning), never varje morgonen.

Would varje change if the noun was an ett-word instead of an en-word?

No, varje is a great word to learn because it never changes form! It stays exactly the same whether you use it with an en-word like morgon (varje morgon) or an ett-word like år (varje år).

Why is there a -t at the end of schemat?

The dictionary form of the word is ett schema (a schedule). Because the sentence specifies 'the schedule', it needs the definite form. For ett-words that end in a vowel, you create the definite form by simply adding -t to the end, giving us schemat.

Kontrollerar looks like the English word 'controls'. Why does it translate to 'check'?

In Swedish, kontrollera is very often used to mean 'check', 'verify', or 'inspect'. While it can sometimes mean 'control' (as in having power over something), checking a schedule, a ticket, or your homework is almost always expressed with the verb kontrollera.