Thanks for the answer, Arkcon the Global Moderator. I tried to use my reptile brain, alas, without any significant progress. But this is how we planned on doing it:
We realized that the salt will be mixed with the water and that whatever the tea leafs emit also will be mixed with the water, i.e, we'll have to deal with a liquid consisting of salt, whatever tea leafs emit, and water.
We realized that we could use some kind of filter to separate the liquid from the sand and the tea leafs. So we planned on first doing just that.
Then we planned on separating the sand from the tea leafs with some other kind of filter that accepts sand cones but not most shapes and sizes of tea leafs.
Then, once we had seperated the sand and the tea leafs from each other and the liquid, we planned on utilizing whatever coal technique our teacher was talking about to extract the tea leafs' "pigment". I will NEVER be able to figure this particular part of the assignment out by myself.
Then, we planned on utilizing "distillation" by boiling the liquid and thereby forcing the water in the liquid to become gas once we reach 100 degrees. The salt, that can't become gas until 1 200 degrees, will be left there for us to do fun things with while the water itself is gas. I don't know how I am supposed to move the gas somewhere safe using the relatively basic equipment that we'll be using and then turning it into a liquid again.
And then, everything will be fine presumably. I still won't know jack about chemistry, though.