I read last night that the College Board deemed only 43% of SAT test takers in 2012 "college ready." The College Board recommended teachers increase the rigor in classes. Check out this problem from the AMC 10/12 math test on equations of lines, slopes, intercepts, etc.
It was a phenomenal way to start class. Most students needed ten minutes to dissect this problem and then we talked about it for another ten.
I had students explain why 4 of the 5 cases CAN work, and why one of the choices cannot work. Try it yourself.
Level 4 will do this one in the next class or so.