So you weren’t around for the American school system middle school civics lesson that to be President one has to be born on U.S. soil. And you can’t prove Cruz was a U.S. citizen at birth. Not that the ruling class or mainstream propaganda press ministry would care either.
If your middle school teacher thinks that Cruz is not eligible, he/she will have to make his/her pitch to the electors and I would suggest that he/she start making that pitch to the voters who select the electors.