There is a pronoun/antecedent agreement problem in this advertisement for Huntington Learning Center. (How ironic!) "Help your child get into the college of their dreams!" is wrong because "your child" is singular and "their" is plural. This could be corrected by changing "their" to "his or her."
I realize that it is obnoxious to say his/her rather than their. It is my humble opinion that eventually it will be acceptable to use their as a singular and plural, just as you can be singular or plural. I probably won't live long enough to see it, though.