Lucy's Lemonade Ledger

Lucy's lemonade stand had a bright yellow sign, but at the end of the first weekend, her cash box only held four dollars. Her older brother Ben opened his notebook. 'Time to look at the numbers,' he said.

Together, they made a simple chart. Sugar cost three dollars. Lemons cost four dollars. Cups cost two dollars. That meant Lucy had spent nine dollars before she sold a single glass. She had sold thirteen glasses at one dollar each, so she had earned thirteen dollars. Thirteen minus nine was four — the exact amount in her cash box.

'You made a profit,' Ben said, 'but a small one.' He suggested that Lucy raise her price to two dollars for a bigger cup, and buy sugar in a larger bag to save money. The next weekend Lucy tried the changes. She counted twenty-two dollars in the cash box — and this time she understood exactly why.