Like Jeffrey, I am wondering what the main goal of your project is. Based on past experiences in biology class, I think that amoebas don't react very well to any stimuli including light and physical/touch.
When you say "simple HS project," do you mean any topic, or is there a specific topic (other than the effects of sound on amoebas), such as zoology or biology, that you are interested in and would like to do a (easy) project on? Narrowing down your field of focus would help us find a topic.
If you really want to work with animals under the microscope, here's an idea. I have seen lots of people do projects subjecting planaria to various conditions and observing any change in their heart rate. The planaria's heart (it is a flatworm) is visible from the outside.
And don't forget to check out the Science Buddies Project Ideas Page. http://sciencebuddies.org/mentoring/project_ideas.shtml
If any of this seems confusing (I know, I crammed a lot into here...
) or you need further clarification, feel free to ask any questions! Hope this helps!
Best of luck!