This is what I remember from the WS (and I scored "S" twice...
the writing sample is "system-based" essay.
When you get the topic, you need to write a brief intro, then use an agreement example, play devil's advocate, then agree again.
sooooo, i think one of our topics was "Speed of technology - too fast for its own good?"
intro - what are you describing as technology...internet, computer, genetics, etc. ie, genetics.
agree..tech moves fast...communication, education, many new skills. ie, we are learning how many disease mechs work and how genes can be manipulated, even in the womb, to treat and prevent problems.
devils advocate...are we creating monsters? ie, now we can clone a sheep...is that where we want technology and genetics to come together?
if you have some sample topics from the MCAT office....write some sample essays..and be honest, time yourself...then show to a professor, and ask them to take a look at them.
I found that as soon as I understood the system, the writing became fairly easy. I did not think either of my essays were very good on the test, but the graders also know that you are working with a limited amount of time and info.
also, FYI...the advice of reading a daily newspaper will assist you in writing a better prepared essay. You will have many examples from the world to use in your paragraphs.
good luck!