Teaching colors, shapes, and days of the week/months of the year, to make sure kids know them, seems to be the thing when kids are little. And I have to laugh a little, looking back, at the sheer waste of time it represents (unless it's just fun to do it, in which case, that's always worthwhile).
I am just as entranced as anyone, at the colorful collection of cute bulletin board supplies and reusable calendars with change-out pockets for days, and different headers for months, at the office supply store. I even recently put up a little chalkboard in what used to be the dining room, with a wipe-clean dry-erase calendar and everything. It's so darned cute! Made me feel good, too.
But I caught myself thinking about my daughter, now 8, and her ease and facility with using calendars and planning and plotting, looking forward to special occasions and how she'd remind me several times a day, how many days away a certain holiday was. And I realize I never purposefully taught her the days of the week or months of the year. Even if no one spoons it into their heads, by 8, they will drag that information out of you, the calendar (on their own), or some other source, and beat you over the head with it!
There is no stopping them. Once they can read for themselves, if you have calendars around the house, the plotting and planning and finding out how long til whatever, begins, whether they ever recited a drill on it or not. So it's totally ok if you completely forget to teach those things. They will still find out and make use of that information, no matter what.
Colors in particular, being taught explicitly, make me laugh, because the names of colors are as much an intrinsic part of our language (and all languages if you think about it) that a kid can't learn their own mother tongue and become a fluent speaker in it, without also somehow knowing the names of colors, even if no one thinks to teach it to them as a subject. Same with shapes. So what happens, if those things aren't deliberately taught at a certain age? Nothing. They still learn it, the same way they learn that sky is that air up there, and water is that clear stuff you drink.
So when products tout that they teach colors, or when curricula teach colors as if they are somehow learned differently from other commonly encountered descriptors in the language a child learns, I find it kind of funny. What happens if no one teaches it to them!? Are they going to go through life ignorant, calling an orange, a Yellow? Ach, if only I had taught them their colors! None of this would have happened!
At least I don't feel the slightest bit guilty, that I don't sit my younger ones in a circle on the floor and recite the colors, shapes, and days of the week with them. Kudos to those who do, particularly if they and the kids enjoy it. But how nice to know, not even lifting a finger in that direction, has absolutely no consequences, whatsoever. Ahhhhh.