Learn Italian: Tutti gli studenti studiano ogni pomeriggio. - All the students study every afternoon.

This is the main rule for these two words! When you use tutti or tutte (all), you must include the definite article (like i, gli, or le) before the plural noun. However, ogni (every) always connects directly to a singular noun, with no article in between.

Does ogni change its ending to match masculine or feminine words?

No, ogni is invariable. It never changes its ending. You use ogni for masculine words like ogni pomeriggio (every afternoon) and for feminine words like ogni mattina (every morning). Just remember it must always be used with a singular noun.

I sometimes mix up plural articles. Why is it gli studenti instead of i studenti?

For masculine plural nouns, we normally use the article i. But if the noun starts with an 's' followed by another consonant (like the 'st' in studenti), we must use gli. You also use gli before nouns starting with a vowel, z, ps, pn, or y.

Why does the verb studiano end in '-ano'?