10, 20, ...

we learn 21, 22, 23, 24 today.
"let's group the items in ten. circle the items of ten. Then count how many items all together in the box."
He circled 2 circles, and left out the remaining. Great!
But he can't count how many altogether.
"Nevermind, let's count together."
"here, 10, another 10, makes 20. 10, 20, and the next number is?"
"30. 10, 20, 30."
"no"
"it should be 10, 20, and 21, 22, 23, 24, etc."
"10, 20, 21, 22, 23, ..."
:)
i know, u are still confusing.