Explain the importance of grouping numbers. Use a pencil or a pen to write the numbers 1 to 9 on a piece of paper. Tell the children that there is one digit in those numbers. Continue to write larger numbers such as 50, 100 and 1000 and tell them the amount of digits that each number has.
Explain the difference between tens and ones by writing "Tens" on one side of a piece of paper, and "Ones" to the right of it. Place a line down the paper separating the the words "Tens" and "Ones." Write out the numbers 0 through 12 in columns, making sure that the numbers 0-9 are written to the right of the line and the numbers 10, 11 and 12 are written with the 1 to the left of the line and the 0, 1 and 2 are written to the right of the line.
Let the fourth graders count in groups such as tens, twenties, thirties, forties and fifties. Tell them that counting in groups is faster and more efficient. Let them know that it is essential to count in groups when there are many objects to count.
Place different colored objects in groups, such as rubber bands. Choose objects of the same size to help the fourth graders picture the object that represents a specific group. Pretend that blue rubber bands are ones, the yellow are tens, and the red ones are hundreds.