In this lesson, students use ten-frames and number bonds to add 9 and another single-digit number by decomposing the second addend to make ten with the 9. For example, they solve the problem "Maria has 9 green cubes. Tony has 3 red cubes. How many cubes do Maria and Tony have?" by showing 9 dots and 1 dot together in a ten-frame, along with two extra dots, and by showing the decomposition of 3 into 1 + 2 as a number bond.