I grew up on a farm in China, where I played with sheep and drew water from a well. Coming to America at the age of ten, I entered a new world filled with technology . Eager to learn everything possible about technology, I volunteered at Southeastern Railway Museum. As I worked with others to repaint train surfaces, replace wooden floors, torch engine elevation plates, and even lift a 100-ton train car with a crane, my knowledge expanded greatly. My most challenging task was to replace a car's brake system. At first, I was clueless on how to do it, but rather than giving up, I sat back and analyzed the entire system for hours. Got it! I gathered the tools and spent the next three months taking apart the entire brake system, then reassembling it with new parts arriving from MARTA. Though I have learned so much, there is still so much more to learn.
This is 848 characters (minus the word "technology"). So I would try to do these things.
1. Instead of saying "technology", give one or two specific examples that struck you initially (If you talk about living on a farm, then say "I entered a new world filled with cars and television", they'll understand that you're talking about technology)
2. You said that your knowledge expanded after doing all of those things. The people reading your essay will want to know what you've taken from this activity besides knowledge or the cliched determination, teamwork, etc. What insight has volunteering their given you about technology and its importance to society? How has your experience impacted you or your goals for the future? I would take out the last sentence and replace it with something that answers one of those questions. I know you're trying to convey your curiosity and excitement about exploring the unknown regions of technology, but that statement is kind of obvious;.
Overall, it's well-written and an interesting activity. Good luck!