For me, all people are intelligent, but not all of us are intelligent at the same things.

Measuring intelligence with just one type of test doesn't make much sense. As the quote attributed to Einstein says: "If you judge a fish by its ability to climb trees, it will think it's useless all its life." And he's absolutely right.

A child may not be very good at languages ​​or at traditional school, but they may be excellent at solving problems, understanding how things work, or doing math in their heads. In Cuba, I met people who did super-fast mental calculations but could barely spell their names correctly. So what? They were just as brilliant, just in a different area.

That's why I love homeschooling, because it doesn't force the child to carry all the mental burden of traditional education. Instead, for example, by seeing that your child is good in one area, you can reinforce that area and not overload them with physics, chemistry, etc.

If a girl loves dancing or swimming, why force her to study the rest in depth until 2 a.m. for a stupid test that she'll never use for anything else in her life?

I'm not disrespecting school; it's just that a child who's very good at math remains stuck in the same mold as the rest of the class because the teacher measures them all the same. In the end, their potential is stunted, and they don't reach where they could have been.

We often measure intelligence with a yardstick that doesn't apply to everyone. And that makes many people feel stupid when they're not. The important thing isn't how much someone knows, but what they're good at. Because we all have something.

The kind that appeases the parents ego

IQ is a normal distribution with 100 as the mean, i.e. it is a relative measurement. So, say you wanna measure a 10 y/o IQ, you just run that result against peers only. IQ is known to be correlated with 'success', i.e. money, happiness, school performance. It might not be a perfect test, but it is indicative (and there lies it's functionality).

But you meant to say how do we measure intelligence. Perhaps the better question is, what is the goal for measuring? What does anyone want to get out of it?

By no means should it be interpreted as a final verdict. All tests have a sensitivity vs. selectivity trade-off. Which means no test can be fully discerning nor fully registering. But you're gonna have to use 'a' test (dependent on the goal).