This is my HL math IA which models the resonance phenomenon of an old-fashioned airplane wing using differential equations (2nd order linear inhomogeneous). To be honest, i'm quite satisfied with it. However, there were a few stuff that I felt like i didnt do my best; such as the technology criteria. I did this IA in exactly 2-week time (at the risk of being kicked out of class for not being done), so i couldn't have time to expand a little bit on my use of technology in the IA........ Anyhow, I got 17/20 (moderated mark), which is basically equivalent to a 7. So i'm glad about it.
PS. For future candidates: I strongly recommend you to choose calculus as your IA topic. It's incredibly fun and rewarding