I wanted to add a bit about how we use Math U See. We do math each day for an assigned amount of time instead of a number of pages or lessons. Some days my kids have flown through several pages. Other days they were only able to complete one page. It all depends on the complexity of the lesson coupled with their understanding of the material.
Math U See was created for homeschoolers so that those of us who don't have a great background in math can still teach our children successfully. Therefore, it will include easier lessons that some students might fly through and harder lessons that others might crawl through. That is why the creator, Steve Demme, says to follow your student's lead. Only do as many practice pages as your particular child needs and then move on. The practice pages often take much less time than the review pages. Also, MUS starts off simple and then gets hardest through the middle, easing up a bit again towards the end of the book.
If my student were only taking 15 or 20 minutes a day for high school level math, I would have them double up on their lessons. If they finish early, that gives them all the more time to pursue more complex math courses, like calculus and trigonometry.
We are just wrapping up MUS Algebra 1 and it has been a good and challenging year for both my daughter and myself. We will start MUS Geometry in a few weeks and I will let y'all know what I think. My son used Teaching Textbooks Geometry so this will be my first run through MUS geometry.
I wouldn't have my child take the SAT or the ACT without prepping extensively before hand. My daughter is beginning her SAT prep with Khan this year even though she still has almost 2 years before she will take the test.
I do plan on using Lial's Intermediate Algebra for Algebra 2 instead of MUS. It is more extensive and will help with learning proper math terms which MUS is weak on. I've heard that Lial's has lots of review of algebra 1 concepts before moving on to algebra 2 and I think that will be a good fit for my daughter. I plan on purchasing it soon so that I can start working through it myself to see what I think.

>>If my student were only taking 15 or 20 minutes a day for high school level math, I would have them double up on their lessons.  This. And that's how it's *intended* to be used. MUS is a mastery program, meaning they are expected to *master* each concept before moving on. If they know the material, they can move on. If they're struggling to get a concept, they spend more time on it. Mr. Demme even tells you that, both in the intro pages of the manual, and in the Intro section of the DVD. Many times, I have had my girls do 23 lessons a day if they already knew *that* material, and keep going at that pace until they hit something harder. Because then there were other times that she/we had to rewatch the video at least two or three times, practice with manipulatives, draw it out on the white board, and go through all six worksheets available, and then still have to practice some more before the test.
If my oldest had stayed with Saxon after fighting through both Alg 1/2 and Alg 1 over a 3year time span, there is NO WAY she would've gotten a halfway decent score on the ACT! I seriously wanted to BURN those books, and I allowed her to stop Alg 1 before finishing the course. I decided to find something "doable" for geometry just to check the box, and was NOT going to require Alg 2 from her.
So we decided to try MUS for Geometry, and she LOVED it! She actually *understood* what he was teaching for a change, and she did so well with that course that SHE decided to go ahead and do Alg 2 with MUS. She only took the ACT twice  the first time after MUS Geometry, and the second time after Alg 2. I don't remember the exact # for her math score, but I know that her composite score went up from 28 the first time to 29 the second time. (Completing Alg 2 was the only thing she did differently in between the two tests, plus taking practice tests with the ACT test prep book.) She chose not to take the ACT again a third time, saying that she was "done" and satisfied with her score. She did have to take the math placement test before enrolling at the community college, though, and placed right into College Algebra.
Confidence is EVERYTHING. I don't care how "rigorous" a math publisher claims to be, or how "easy" it appears (to some) to be... if the student is afraid of math, they will NOT do well on standardized testing. That's just a fact. Not every publisher or teaching method works for every kid, so just because some kids (or parents) don't like Publisher A doesn't mean it's a "bad" math program, just as Publisher B isn't a "bad" program just because others don't like that one. I *LOATHE* Saxon for OUR family, but I know many (both personally and online) who love it and have done well with it, and I still recommend it to those for whom I think it would be a good fit. But MUS is a great fit for *other* people.
I have a personal friend who used MUS from beginning to end with her six oldest kids (she has nine; not sure what she's using with the three littles), and the only two of the four she's graduated so far who've shown any desire to go to college, have done so very successfully. In fact, one of them is as she describes an "academic" who's going into premed on scholarship. Obviously, MUS didn't do her any harm. ;o)
Oh, and my oldest? She's no longer afraid of math. In fact, she now *enjoys* it, and she's the one I call for help when *I* get stuck teaching her sisters! And if she's still working at Walgreens in six months, she plans to do their Pharmacy Tech program, which of course involves a lot of math and chemistry. ;o) But in college, the only math course she needed for her degree was Business Math, which she *excelled* in. She was the best student in the class.
My 2nd dd did fine with MUS all the way through high school, too, but she hasn't taken the ACT at all because she's pursuing a dance program rather than college.
And that's the other point, too... not all kids *need* a lot of intense higher maths in high school. Why subject them to the hardest math program on the market "just because"? Being more "rigorous" is FUN for some people.... but sheer torture for others. And simply not necessary for many. (I would even dare say MOST because there are many, many different ways to accomplish high test scores and college level classes when the time comes... IF they even *need* that.)
