If he's around 8-9-10 years old don't lie to him or make up phony reasons. He'll see right through it and lose all respect for you. Like the generations raised

If he's around 8-9-10 years old don't lie to him or make up phony reasons. He'll see right through it and lose all respect for you. Like the generations raised in the era of "everyone gets a sports trophy" BS. Now we have multiple generations of low self-esteem, bitter cynics. Tell him the truth, you use it as a programmer but you don't know what he'll want to be when he grows up so he may never use it. Tell him the truth, that algebra is the base[1] of more advanced math like geometry or calculus and used by engineers and scientist and maybe someday he'll want to be an engineer or scientist. Tell him the truth that as hard as it seems now, if he needs it later (but doesn't know it) to become what he wants to be it will cripple his chances and limit his choices. Tell him the truth, you are the dad and in your judgment he should know algebra even if he doesn't use it because it is difficult but will make him a better thinker which has value in ANY endeavor he may choose. [1] As an ex-teacher, it has been my experience that when students struggle in math at level Y they didn't really learn level X, the preceding level, in the previous semester or year. (Alternatively, they are just dumb). At a certain age kids learn that they can just fake it and learn the mechanics of mathematical manipulation of the symbols with virtually no understanding of the underlying concepts or relationships. This is the end of their mathematical training. After that it is training parrots or monkeys. So my advice is to check and review his earlier work. He might have faked understanding it or just plain forgotten it.