Sixteen words sit in a bank at the top, and below them a T-chart waits with A on one side and AN on the other. A child reads each word, decides which article it takes, and writes it in the matching column.
The sixteen split exactly eight and eight, and the chart gives eight numbered lines under each heading, so the page checks itself. A child who fills seven lines on one side and nine on the other has found a mistake without anyone marking it. Words like owl, igloo and umbrella sit next to cat, frog and bus, which keeps the vowel sound doing the work rather than the length or difficulty of the word.