A solution looking for a problem
If you really want to get kids more knowledgeable about geography, it might be more worthwhile (and more fun) to teach them about earth coordinates. Locating the spot antipodal to your house is simply a question of flipping the signs on the coordinates of your starting location. This would have the added advantage of teaching them to use an atlas
You can do it in your head, My antipodal lat/lon is approximately (S26d, E80d).
Incidentally, the software put my antipode 180 nautical miles east of where it should have been.