Dear Sesame Workshop,
I am 40 years old. 4, 0, FORTY years! [Thunder, lightning] Ah, ah, ah, ah. . . . . Yet I distinctly recall playing hide & go seek as a 4 year old boy. My uncle asked me to count to 100 so everyone else could go hide well before I went searching for them. But I had to tell him I didn't know what that was. I had only learned to count to 20, because that was the highest number Sesame Street would teach at the time. Even then, none of the other kids took the time to teach me what they knew, they just wanted to play the game. But I'm certain I could have learned how to count to 21 & beyond, if only they had taken a moment to explain it. I missed out on learning that until the 1st or 2nd grade.
I think children are capable of learning much more math, much sooner. If the Sesame Workshop had just played some shorts explaining numbers up to 100, I think I would have quickly figured out that the pattern of increasing numbers and their names continues to at least 999, at which point I certainly would have asked adults on my own, "What comes after that?", and they could easily handle explaining 1000+.
There is one problem with numbers in American English that is invisible and built-in. The teens and their names.
10 should be called "tenty"
11 should be called "tenty-one"
12 = "tenty-two" and so on up until 19 = "tenty-nine"
When you consider that all numbers above 20 have the same naming pattern, but the numbers 10-19 don't, then you realize that teaching numbers just up to 20 means a child is going to presume every number has a special name that someone else must share with you before you can name it, or use it, just like people have names that are unknown until an introduction is made.
So please consider increasing from 20 to 100 the maximum number that Sesame Street teaches. You could even make a song about how it makes no sense that number eleven should be "TENty-one", but that sounds too similar to "TWENty-one", especially on the phone, so we call it eleven instead. You might make a joke that maybe we could call it "ONEty-one", but that too sounds too much like "twenty-one" on the phone, the radio, or TV.
You might find it helpful to present the number and the word for the name of that number at the same time. I know Sesame Street hasn't normally done that in the past, but I think it might be time to start, with the basic numbers especially, as this could help children learn to read much faster too, as spelled-out numbers are everywhere around us.
You might determine I'm wrong, that this is too hard for children this age (for all I know, you may have already tried it before). Maybe trying to explain how the teen numbers break the normal pattern is too much for your TV show. Perhaps just a few rare showings of segments about these larger numbers & teen-names is all that older children will need to clue in & pay attention that this is important, because they rarely see the skit about this.
But whatever else you do, please increase from 20 to 100 the maximum number that Sesame Street typically teaches.