Core Value: There is no balance
"A balanced life is a lie." ~ Gary Keller
Yep, it's true. Would you rather have kids committed to success or evenly distribute their time to multiple endeavors, creative or cookie cutter, insightful or unaware, leading or listening to others, strategic or obedient. If you chose the former in all the the cases, which I hope you did, then you chose someone who isn't going to be balanced in all aspects of life or education.
I'm pretty much going to quote Gary Keller's book, The ONE Thing, for the rest of this idea; "Extraordinary results are directly determined by how narrow you can make your focus." We all agree on the greats in anything, great painters are great painters, they aren't great plumbers or computer programmers. What about great athletes? Look at all the scandals going on between 2010 and 2014. Athlete after athlete is under the microscope for what they have done. Are the things they have done wrong, absolutely. They point being we were so focused on creating ridiculously awesome athlete we forgot they should probably learn some morals.
If you are going to build an extraordinary life; a life of passion, giving, caring, success and love, it won't be a balanced life. Furthermore, if you want kids to do math, give them a reason to do it. If they are interested in drawing and design, they will learn the necessary math to do so. They don't need to know how to know the FOIL method. If they want to get into politics to change the world, they will need to learn how to read and ask questions and type and spell, they don't need to know what the inner wall of a cell is called.
The point here is that through passion we actually will balance ourselves, exactly as much as we need in order to survive. Funny thing is, you don't need anyone to tell you how much that is, your brain just knows.