When I gave a worksheet today, 2 of my students labeled this notation as 3/4 time, simple triple. Are they wrong or is this acceptable? If it's not acceptable, why? Is it simply because it wouldn't make sense to use 2 eighth rests at the end here in 3/4 time?
6/8 is duple time - the bar is split into two equal parts. With the first note, a dotted crotchet, it makes the first half. There's no reason to have two quaver rests at the end in 6/8 - a crotchet rest will suffice. Having said that, it would also be fine in 3/4 time, which would query the dotted crotchet at the beginning, which may be more acceptable (in 3/4) as a crotchet tied to a quaver.
But, we see this sort of thing more and more - notes across the middle of 4/4 for example, so perhaps we just need to get used to what used to be called sloppy writing...
As an aside, should one give out work that one hasn't scrutinised for potential discrepancies, with all possible answers researched? Maybe another way to read it is using notes in place of rests. As in, would the last note have to be two tied quavers, or would a crotchet be acceptable?
If this were 3/4, 'old' theory would demand the dotted quarter was written as a quarter tied to an 8th. OK, we don't always do that now. But in 3/4 the bar would be completed with a single quarter rest, not two 8ths. We can't wriggle out of that one! It's 6/8.
The grouping of the rest tells you it is 6/8 time.
If it was 3/4 time the last two quaver rests would be a crotchet rest as to better indicate the crotchet beats, this time signature has two beats of dotted crotchets that is better illustrated with the given rest grouping.
To the best of my knowledge, they are not the same. 3/4 feels like there are 3 "binary" beats each bar. Think of waltz. 6/8 feels like there are only two beats and where each beat can be felt as having 3 subdivisions. So it's a matter of figuring out the "beats" that there are on the bar cause they feel completely different. Coming from Venezuela myself, I know in venezuelan music there are some types of music where they can be mixed (and which is very tricky to figure out for people from other countries). The best example I can think of right now is "Preludio Criollo" by Rodrigo Riera where he has the bass voice going on 3/4 and yet the main voice is going 6/8. Tricky to play. Talking about (venezuelan) genres, probably Pajarillo or other varieties of Joropo like "Seis por Derecho" are the hardest to pick up.