Around the age of pre-k and kindergarten, a rationalist parent can probably do best by modeling and responding to learning and exploring the world -- responding to all those many why-questions, along with carefully narrowing down their appropriate use; building vocabulary; and modeling that you expect to find answers to questions (let them see you Googling!).

Young kids learn a lot from the modeling of their parents, and treating the world as explorable and knowable is a very good thing to model.

Unfortunately, they will get a lot less of this sort of modeling, and a lot more formal curriculum, in the average elementary school. YMMV, of course, but in general the best academic thing you can give to a young kid is your knowledge-seeking personality.

Curriculum for very young kids might be better used as a guideline; for example, the tasks demonstrating tone might remind you do say "oh, he sounds angry" either when reading aloud or when someone really does sound angry. But the odds are if you are playing with your kid, you will already hear them make their toys talk in angry, sad, scared, etc. voices. Likewise with the vocabulary; your kids should be picking up synonyms from regular conversation (at this age, more understanding than using), and are primed to learn best from natural conversation, not guided lessons.

Which is not to say that if you do find the curriculum beneficial that you are doing something wrong (in fact, using additional resources for better results is doing something right -- as long as you are checking that you do get better results). My point is only that curricula generally gains value as kids age, and is usually more valuable in a classroom environment than in a home one.