Lucas sat beside Ben as their maths lesson began. The teacher wrote some sums on the board. She invited Lucas to solve one for the class. He worked it out and wrote the correct answer. Pleased with his effort, she asked him to sit down. As Lucas returned, he noticed Ben looked worried. His friend was struggling to understand the task. Rather than leave him confused, Lucas offered help. He decided to explain it with a simple drawing. On a sheet of paper, he drew ten circles. Then he crossed out three and pointed to the rest. Ben counted seven circles that remained. The drawing helped him understand subtraction. He tried the next sum without any help. When he got it right, both boys smiled.