This test chamber has some nasty poison on the floor, and the computer warns you that it will kill you if you fall into it. There is a high energy pellet here, and you will have to make a blue portal on the wall where it has made a dark mark. Then, after it goes through the orange portal, make a second blue portal on the part of the wall where the containment thing is shining a light. The pellet will bounce from the wall and go back through the orange portal, flying through the blue portal that you just made, to enter the containment thing.
Now comes the difficult part. You need to first make a blue portal on a wall that you can reach from where you are. Go through it to get to the platform where there is an orange portal. Now, you need to make a blue portal on the ceiling above the unstationary scaffold, and go through the orange portal when the scaffold is under the blue portal. This is dangerous, because if you don't put the blue portal in the right place, you will fall to your death. My advice is to create the blue portal, then look through the orange one to check that the scaffold is under it when it stops.
The computer assures you that any appearance of danger is only to enhance your testing experience. However, this computer has been known to lie (and even to admit to lying), so I wouldn't trust her.