Common present-tense slips
Ten minutes on the topic's own four common mistakes: a bare infinitive left standing as the sentence's verb, the -ам ending forced onto an -им-group verb, a made-up -ију instead of the real third-person-plural -е, and an -овати verb keeping its infinitive stem instead of switching to -уј-. Build sentences around watching a film and speaking English, catching each slip in turn, before the unit's own listening and reading put the whole topic to work.
The part of the grammar page this lesson drills — read it here, then use it.
Group I - the -ам group
Most verbs whose infinitive ends in -ати belong here: drop -ати and add -ам, -аш, -а, -амо, -ате, -ају - the largest and most predictable group, with no stem changes.
Group II - the -им group
Verbs whose infinitive ends in -ити, plus many ending in -ети, belong here: drop -ити/-ети and add -им, -иш, -и, -имо, -ите, -е. The 3rd-person plural ending is -е, not -у - a frequent point of confusion.
Group III - the -ем group
The fully regular, highly productive corner of this group is -овати/-евати verbs: drop -овати/-евати and add -ујем, -ујеш, -ује, -ујемо, -ујете, -ују. Spotting an infinitive ending in -овати tells you the whole conjugation.
Other -ем-group verbs exist too, often with a stem change (see the exceptions below) - those are covered in a later lesson, once you have more vocabulary to practice them with.