You want Emmett to register as no longer a model citizen. So everything on the slide show that Edna would think should register positive thoughts, you need to make negative and vice versa.
The hotspots are very close together here, so that makes it more difficult than it would be otherwise.
There seem to be two ways to get Emmett to think reister "positive" (green light on his head) -- the record player and the soup. There are two ways to get Emmett to register "negative" (red light on his head) -- the fish tank and the generator.
I did the whole challenge using just the record player and the generator, but I'm assuming you could use the other two if you wanted. (I found sometimes one blast with the generator would only bring a neutral (yellow) response, but a second blast would send the light to red.)
Start the test, get Emmett to register the correct opposite response, then push the slide button to get to the next slide, and keep going.
When you've done everything right, some of the machinery (I think the slide projector) blows a fuse so you can't do any more tests.
