Today's math lesson with my almost 5yo:

Me: today I'm going to teach you how to count fast. We're going to count by 10s. Today we'll stop at 50.
Z: 1,2,3,4....(with a little help goes all the way to 100). What comes after 100?
Me: 101 (sigh)
Z: 102, 103, 104....(needs help with 110, but gets the idea & keeps going). Hey, I only wanted to count to 100! Now I have to do it again. 1,2,3,4,5....(with help, reaches 100 for the 2nd time). 101, 102, 103...(goes up to 110 again). Hey, I only wanted to go to 100, now I have to do it again! 1,2,3,4...(counts up to 100 with minimal help), 101...
Me: STOP! NO MORE! STOP! STOP AT 100! (LOL). Remember, you only wanted to count to 100?
Z: now I need to start all over again!
Me: no, that's enough!  You did it the slow way, counting by ones. Today we're going to learn the fast way, counting by 10s. We're only going to count to 50. You've never done this before.
Me & Z: 10, 20, 30, 40, 50
Z: 60, 70, 80, 90, 100.
Me: uh, Ok...I guess you know that! LOL.

Sometimes I wonder why I try to teach anything at all!