Summarize the following:
Tell children that all the numbers from 11 to 19 are made up of one ten and a number of additional units. The number 20 is made of two whole tens. Help children visualize this concept by writing the number 11 and, next to it, showing a ten and a single unit, separated by a circle. A ten frame has 10 empty fields, which are filled as you count. You can use coins or other small objects to demonstrate this, and you can also draw it on the board. For a good activity, give each child two ten frames and 20 objects of some kind. Have them create the number 11: one full ten frame, and a second ten frame with just one unit in it. Have them create the other numbers. You can also reverse the process, starting with full ten frames and taking objects away. Show children that you can represent these numbers with dashes and dots: dashes for tens and dots for ones. Demonstrate that the number 15, for example, is made of one dash and five dots. Draw a T on a large piece of paper. The left column represents tens; the right represents ones. Fill the right column with the numbers 1 to 10, in sequence; leave the left column blank. Then:  Add representative numbers of objects, such as small cubes, to the ones column: a single cube next to number 1, two cubes next to number 2, and so on. Explain that you could represent a ten with either ten of the small cubes or one larger stick. Fill the tens column with sticks, one by one, and explain how these numbers would work together to create larger numbers.
Explain the basic concept of tens and units. Introduce ten frames. Try using dashes and dots. Draw a T table.