The Case of the Gooey Cookies

The school day was almost over, and Ms. Vee was discussing the upcoming field trip to the science museum. As she spoke to the class, she taped a sheet of paper to the back wall.

“Remember, we’re holding a bake sale during lunch on Monday to raise money for the trip,” said Ms. Vee. “Sign up here for an item to bake.”

After class, several students crowded around the sign-up sheet.

“I want to make chocolate chip cookies,” Sadie told her friends Jason and Nico.

“Hey, I wanted to make those!” said Jason. “I guess I’ll make something else.”

“I think we all can make them,” said Sadie. “There are three types of chocolate chip cookies on this list—white chocolate chip, milk chocolate chip, and dark chocolate chip. I’ll take white.”

“Milk chocolate for me,” said Jason.

“That leaves me with dark chocolate,” said Nico. “But it’s not my favorite. It’s not as sweet.”

“Well, dark chocolate has the least milk and the most cocoa,” said Jason. “So it’s bittersweet.”

“And white chocolate has the most milk and the least cocoa in it,” said Sadie. “It’s so creamy.”

“That’s OK,” said Nico. “Making dark chocolate chip cookies just means I won’t eat any of my cookies before the bake sale!” Nico and his friends laughed.

On Monday, Ms. Vee’s students gathered in the cafeteria before lunch. Ms. Vee handed them gloves and plastic bags. She instructed them to place each baked good into a bag. Sadie, Nico, and Jason took the first shift selling snacks.

“Each baked good will cost one dollar,” said Ms. Vee. “Nico, you’ll collect the money and make change.”

The bell rang, and students strolled in. Many stopped to buy a treat at the bake sale booth on their way to the outdoor courtyard.

“These snacks look great,” said their friend Julie. “But it’s so hot outside. You guys really should be selling ice cream!”

“You’re right,” said Ms. Vee. “This weather is so unusual for fall.”

After the bake sale, Nico started counting the money. Before he could finish, a group of students approached.

“We want our money back,” said Tina. “We bought these chocolate chip cookies, and look . . .” She held up one of the plastic bags. “They melted before we even got to eat them.”

“I’m sorry, but I don’t think I can give you a refund,” said Nico. “It’s almost 90 degrees outside.”

“I think you messed up the recipe,” said Tina. “My friend outside had a chocolate chip cookie too, and his isn’t a melted mess like this one!”

“That’s so strange,” said Sadie. “Look, only one type of chocolate chip cookie has melted. The others are fine. How can that be?”

“They must be underbaked or something,” insisted Tina.

Sadie picked up one of each type of cookie. “There’s nothing wrong with these cookies,” she said. “I think these chocolate chips have different melting points—and I can prove it!”