Anomalous Materials is a short stage and is extremely easy. You can walk around some of the Black Mesa facilities, get to see some of your co-workers, see some cool machines, and even make your co-workers angry!
The Anomalous Materials Labs
Wait for the large brown door to open and you will get your first glimpse of Black Mesa. There are many fun things you can do in the main entrance. For instance, in the very left corner is a small computer. Walk up to it and press your use key, (default 'E') and it will turn on. A scientist nearby will be very displeased with you.
Another fun thing you can do is to go to the security desk and press the small red button under it. This will trigger the alarm system, which will make the security guard and scientists angry. None of the scientists or security guards will want to talk to you, exclaiming they are "too busy" or that "you'll just have to wait until after the test."
You can also visit the other end of Anomalous Materials, where you will see a familiar character. You can also turn off a lightswitch in one of the rooms to tick the scientists off. However, you are not allowed into the Black Mesa sewer system, so there's not really a point in going down here.
When you are finally done looking around, look at the color panel guide on the wall. We want to go to the Personnel Facilities, so follow the green panel until you reach a corridor. Step through this corridor and a loadzone will trigger.
Getting Your Hazard Suit
Take a right when you enter the corridor, and keep on going down the hallway. Along the way, you can see a scientist trying to get a soda. Sadly, the soda machine does not work, and the scientist gets angry. You can cause further annoyance to the scientist by repeatedly ticking the microwave until his food is overcooked and blows up. At the end of the hallway is the locker room, where the hazard suit is located. When you enter, a scientist nearby will complain about having to wear a ridiculous tie. Anyway, take a left to go inside the hazard suit storage. Press the button in the middle to release the hazard suit. Grab it, and go back into the locker room.
Open the locker labeled 'Freeman' to pick up a battery. When you are done, exit the locker room and go back to the corridor.
Now follow the blue panel to get to the lower levels. When you reach the end of the hallway, a security guard will unlock the door (you cannot get past this door without your hazard suit). A loadzone will trigger once you step through the door. Go either path, as they will both lead to the elevator. Open the elevator doors and either use the elevator or climb down the emergency ladder to the side (the ladder is much faster). When you get to the bottom, step on through the doors and just follow the blue panel that's in the next room. Along the way you'll notice a huge laser storage room and a room where large water pumps are kept.
When you reach the end of the path, go inside the Control Room. Three scientists are waiting, and you cannot exit the room until they are done talking. Once they are, one of them will open the next door for you. You'll notice two scientists commenting on how poor some of the equipment is after one of their machines break. Go down the small elevator in this room and you will go to the bottom floor.
Now follow the large red panel which says 'Test Chamber' and you will enter a small room with two scientists. You cannot exit until their discussion is over, and when it is, they will open the large door in front of you.
You're finally in the Test Chamber and ready to perform the experiment. The doors close behind you, so there is no way to get out. The scientists will get on a mic, and ask you to activate the rotors.
Do so by climbing up the ladder to the right. You will then be on a platform, where switch for the rotors is sitting. Press this switch when the scientists release the lock. The gigantic machine will then start to heat up, and will eventually become extremely powerful. There's nothing else to do for awhile except sit back and watch.
When the time comes, the specimen will arrive on a carrier. Push the carrier (by walking into it) into the huge generator in the center and immediately step back toward the large doors. The stage will then end after some strange events occur...