I agree with all of the posters who asked how competitive a college your DD would like to try and attend. If she is even considering Ivy League or any other very selective schools, then yes, she should take the most challenging curriculum she can and get the very best grades she can. And although LisalovesPooh stated that you can get college credit with an AP test score of 3,4 or 5-many of the more selective schools now only give credit for scores of 4 or 5. A score of 3 more and more often gets you nothing.
And in terms of what the admissions office will be looking for on a college application, the number one item is academic rigor, GPA, and class rank. Standardized test scores come after that, and academic awards, research, and other notable accomplishments after that.
And this from a former senior admissions officer from Harvard:
"Students often asked me if I'd rather see a student get a B in an AP class or an A in an honors course. Like many admissions professionals, my sardonic response was always, 'Get an A in the AP class.' I would follow the quip with a smile and explain that colleges want to see students perform at the
highest levels possible. (italics mine) If that meant getting a few B's in AP classes, I would prefer those results every time; however, if modest results were also cutting into your extracurricular time as a musician or a debater, then I might recommend finding a different academic balance."
It is still very early in the school year. I might wait to see how it settles out for your DD. My DD is a junior this year as well and in two AP classes (Physics and Language/Composition) as well as Honors PreCalc and Honors French III along with the top choir (A Capella) and her extracurriculars, so I know how you are feeling.
Hope things work out for the best
