Not sure what the requirements are for your class. Best to ask your teacher this question.Interval training is important. Play a note on the piano then sing a note that is an interval ABOVE this.Intervals: minor 2nd, major 2nd, minor 3rd, major 3rd, perfect 4th, tritone, perfect 5th, minor 6th, major 6th, minor 7th, major 7th., octave. After you sing the note, play the correct note on the piano. Hopefully you match. After you get good, sing an interval BELOW the given note..
This may sound corny, but it actually helped me a lot to associate intervals with the beginnings of songs - for example, Happy Birthday starts with a major 2. Star wars is a 5th. Brahms lullaby is a minor 3. My bonnie lies over the ocean - Major 6. You get the picture. Eventually you won't need this, but it can help you get through the frustrating step of all the intervals getting mixed up. This is of course assuming that you can hear a 2-note chord and distinguish the individual notes.
I've been struggling with ear training for about 3 years. I started from zero. I use an app that tests melodic and harmonic intervals, inversions (major and minor 5th chords, and major, minor, dominant and halph diminished 7th chords), melodic dictation and chord progressions of basic chords. It was very difficult for me, but it was such a marvelous thing to learn that I cant umderstand now what is the point of studing music without learning this. What really worked for me was to sing the intervals solpheging. For example, dont say "perfect 5th", but "do-sol", than "re-la", etc. Sing aloud everything. This works magic!