Structural Engineering Challenge 3.0
Being a very proficient mathematician (go ahead, laugh), I love putting my mind to the test with difficult calculations.
While Structural Engineering Challenge doesn't have derivatives and integrals, it does offer a realistic Physics model designed to test the durability of a foundation.
While that may sound a little stale, it is actually pulled off fantastically. By creating a structure focused around a point of pressure, you can evaluate the best way to support it. By slowly adding more weight, you can see which parts of your construction need more support. There are many different challenges, ranging from bridge-like to shelf-style building.
The interface is clean and efficient, with smooth animations representing the buckling (or not buckling) formations. It's worth a download; you'll be surprised to see how fun it really is.