This is easy to make. I took some of the precooked black tapioca (cold from the fridge) and put some in the bottom of a glass. Pop this into the microwave because if you like your balls hard (tee hee), that's what they will be if you don't soften them up. After the tapioca is heated (will look dark and glossy) add some sugar to taste. The warmth will dissolve the sugar, so this is a good thing.
Put some ice in the glass on top of the tapioca. Bring water to a boil and brew your tea in a separate glass or cup. I usually use less water to make a very strong tea. You're going to pour the hot tea over the ice in the glass and this will dilute it a bit while cooling it down.
Stir, put in a big-ass straw (can usually find these in Asian food stores along with the tapioca) and enjoy!