At the end of Episode 1 you will need to mix up a batch of Emmett's Rocket Fuel.
Turn on the Subtitles, the keywords will appear onscreen in capitals.
Ignore Emmetts father, he also says some of the keywords so make sure you only listen to Emmetts instructions.
Emmett will be arguing with his father, and you'll need to perform one of four activities in the correct order. Emmett will be giving you hints, so pay attention to the words he emphasizes. There are four stages, with the last one being fairly rapid fire.
Release Pressure Valve = "bladders," "bags of gas," anything to do with releasing or pressure
Stoke Fire = anything to do with heat or fire
Turn Electrical Crank = "spins," "shock," etc.
Bacteria Food = "microorganism," "eating," etc
If done correctly the trophy will unlock after the cutscene. If you make a mistake reload the auto save to try again.