<p>At a challenging school, high school multivariable calculus may not be sufficient preparation for a prospective math major. Have your son look at these lectures and see if his class covered all of the material:
<a href=“Multivariable Calculus | Mathematics | MIT OpenCourseWare”>http://ocw.mit.edu/courses/mathematics/18-02sc-multivariable-calculus-fall-2010/index.htm</a></p>
<p>(Don’t get me wrong, even reaching single-variable calculus is good enough for a math major, but it’s important to cover the “basics” before moving on to bigger and better things.)</p>