The starting point is: one kid has been killed by Ed. The second kid has got the record, the wax fruit and the fruit drinks. The third kid is in the dungeon with the card key and the glowing key.

With the second kid, go to the kitchen and open the fridge. Then get the (blank) tape, go upstairs, record the tape, get to the Green Tentacle corridor, and give it the wax fruit. Then wait for the "Gee, I'm hungry!" cutscene (this is a good time to open the lab door if you haven't done so).

After the cutscene, give the fruit drinks to Green Tentacle and enter the dark room. Wait there so Ed doesn't catch you (seven seconds or so; you can finish opening the lab door if you haven't done so). Then get to Green Tentacle's and give it the tape.

After the second kid has died, enter the lab with the third kid and wait for the "Ed in the kitchen" cutscene. Now get past Purple Tentacle, and finally get to the meteor.