I often hear it quoted that "the glory of God is intelligence, or, in other words, light and truth" (D&C 93:36).
This is immediately related, by the speaker, to education. It is claimed that if we go and do academic studies at a state or private learning institution, our intelligence will increase. Yet that interpretation detracts from the real message being delivered there in D&C 93. If our education facilities were teaching just truth, that would even then only have slight relevance. The truth and light referred to in this section are spiritual truths that will cause a person not to sin.
The verses following the one above say, [verses 37-39] "Light and truth forsake that evil one. Every spirit of man was innocent in the beginning; and God having redeemed man from the fall, men became again, in their infant state, innocent before God. And that wicked one comes and takes away light and truth, through disobedience, from the children of men, and because of the tradition of their fathers."
This doesn't seem to refer to our ability to add and subtract.
Intelligence is increased, not by going to school, but by accepting spiritual truth and obeying it (as is demonstrated as the obvious converse of the scripture text quoted above).
It seems to me that our level of intelligence is demonstrated by our ability to take in correct information, recognise and reject false information, and then the right application of that correct information.
Therefore the school where intelligence is achieved, is where we listen to and follow Heavenly Father, Jesus Christ and the Holy Ghost, as instructors.