Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (such as 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
Understanding how to use a ten frame is an important step in understanding place value. The students have had practice using a ten frame with smaller numbers, now they get a chance to use it with bigger numbers.
This lesson is to be taught AFTER ten-frames are understood. The concept of place value is challenging to young children. This lesson helps them understand that teen numbers are made from one ten and extra ones.