Oh please! Anyone can get a grade equivilent exam available from a public school. The state would face a huge lawsuit for applying un-equal standards in testing. Theres no way in hell the state would risk giving a 7th grade equivilent test to a home schooled 4th grader and expect it to be the equivilent standard without being forced to apply the same standard to the public school kids.
Most certainly the gummint is not entitled to require that my children or anyone else's be taught "fisting" techniques, taught the wonders of Heather has Two Mommies or Daddy's Roommate, or taught that sexual activity is some sort of constitutional right for 12-year-olds. Much less is the gummint's P.S. 666 entitled to sneak 14 year old Jezebel off to the nearest Planned Barrenhood abortion mill to "confidentially" cover up her P.S. 666 approved social behavior that led to her condition so that only the skewel officials and NOT her parents will know what she is up to.
The gummint and ITS skewels are also not entitled to keep the kids abandoned to those skewels in academic ignorance while providing all the bells and whistles (at taxpayers' expense) like football, basketball, hockey, swimming pools, polo ponies or whatever that makes gummint edjamakashun about 4 or 5 times as expensive as private education and no more than 20% as effective in the delivery of knowledge.
I have no right, even as a taxpayer, to force gummint skewels to teach Catholicism. Atheists have no right to force those skewels to teach atheism. That is in the nature of the commonly tax-funded monster known as gummint edjamakashun. By teaching nothing on religion (and what could the gummint skewels teach on religion short of civil war?), these skewels teach, by omission, that religion isn't very important. I don't want to subsidize that particular lie. Jefferson, not himself a very partisan denominationalist, did observe that there is no tyranny worse than one which forces a man to subsidize ideas which he hates. And no, that tyranny is no more justified than Catholics making Catholic education of non-Catholics in gummint skewels mandatory.
Fortunately there is an obvious solution to these problems without further subsidy of gummint administered ignorance. Erect a (what shall we call it? I know:) "wall of separation" between gummint and education. No one then forces me to pay to entertain their children. Nor do they have to pay for mine. Those without kids don't have to pay at all unless they wish to pay.