Seventh Chords

[Samuraid]

Does anyone know about these in and out? Because I need help. I'm confused about the process of identifying the types. For our homework, my teacher wants us to notate them in this format: M (or m depending on whether the triad is major or minor) followed immediately by M (or m depending on whether the 7th is major or minor)

So for example:

We have G as the root, B as the third, and D as the fifth, and F as the seventh, so it would identified as "Mm7" because the triad is Major and the seventh is minor.

Here's the confusing part: do I identify it in the way I mentioned above or do I identify the chord as a dominant seventh chord since the triad is major and the seventh is minor?

I've never seen such notation used before. Generally, the first letter indicates the root key of the chord, the second letter (or letters) indicates the type (Major, minor, augmented, diminished), and the subsequent numbers indicate the added tones.

Example:
G7 = G dominant 7th
Gm7 = G minor 7th.
Gmaj7 = G major 7th.
Gdim = G diminshed.
G7b9 = G dominant 7th with a flatted 9th.

To answer your question, G - B - D - F comprises a G major chord with a minor 7th on it. (Although the real world simply calls it a G dominant 7th chord)