Do you have a laser diode? Or a DVD burner you can get one from that no one will miss?
The 100 ohm pot helps to adjust the current (the volume of electricity flowing) to the diode.
You will need a few other parts as well, and you can get them mostly at Radio Shack if there's one near you. 1N4001 diode, 47uF ("micro-farad") capacitor, LM317T voltage regulator chip.
You'd also do well to NOT go strictly by the video, but look at the how-to on the site here:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612
You'll see a step by step writeup there.
Also, if you're new to this, BE VERY CAREFUL! These diodes can put out a LOT of light and can cause you and people around you some real problems if your foolish. Besides, it makes it all that much more fun if you have to hand out laser safety goggles to people and tell them to "Stand Back!" before you turn the thing on!
Remember that if this is for a science project, then they're not just going to want to see a pile of parts that can burn things - they're going to want to know that YOU KNOW HOW the diode burns things. What's so different about laser, or "coherent" light that it can burn things powered only by a few AAA batteries? If you can provide an effective writeup on the how and why of lasers, it'll boost your grade a lot too.
Lasers as a hobby can be fun. If you decide to follow up on it and get into a laser-electrooptics program in school, it can be an exciting and fun career - and lasers and light-logic is what's coming up. 10 years from now, we'll have computers no longer based on electronic circuits with wires and foil PC boards, but all fiber and light, with lasers driving the whole thing. Computers will be 1000x or more faster than they are now, with storage capacity measured in quads (one quad = 1000 terabytes, or 1 million gigabytes). If you're well skilled in lasers, you'll be at the forefront of this movement and well suited for a long career.
So head on over to the tutorial at
http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612 and have a great time.
Also - there's a LOT of very helpful and knowledgable folks here, but we all expect you to read the material first and come with an "informed question" - meaning that you know exactly what info you need and you've stated it well because you've read as much as you can from the other forum posts. That way you make it easier for US to give YOU exactly what you really need, without having to teach you the basics that are up here already, free for the taking.
Have fun, be safe, and welcome to the forum.
D