Article
Illustrations by David SanAngelo

The Case of the Hungry Hamster

Caleb Craft is a detective. Caleb loves math. He also loves mystery! Can you solve this case with him? Read the story carefully. Then think about the math clues.

By Jessica McKenna-Ratjen
From the February 2023 Issue

Learning Objective: Students will divide whole numbers by unit fractions to determine how long an amount of hamster food will last.

Lexile: 590L; 520L

Everyone in Ms. Smith’s math class buzzed with excitement, including Caleb. February break was starting tomorrow. They were going to be off for the next week and a half!

“I can’t wait,” Hiro said. He stretched his arms behind his head and sighed. “I hope Ms. Smith doesn’t make us do anything too hard today.”

“Speak for yourself,” Caleb grinned. “You know my favorite thing is a math challenge.”

“Good afternoon, class!”
Ms. Smith called. “I know you’re all anxious to start your vacation. So I thought we’d do something fun today.”

“Yes!” Hiro quietly cheered.

“I believe you’ve all enjoyed taking care of Dorothy for the past month?” Ms. Smith asked. The whole class nodded in agreement.

Dorothy was the new class hamster. The students named her after Ms. Smith’s favorite mathematician, Dorothy Johnson Vaughan. Her cage sat on a cabinet, which held all her supplies.

“Well, I’ve found a pet sitter who can care for her all 12 days of the break. I want him to have everything he’ll need during that time. So you’re going to help me plan my trip to the pet store.”

Ms. Smith drew four columns on the board. She labeled them Food, Treats, Bedding, and Chew Toys.

Ms. Smith’s math class was excited. Caleb was excited too. February break was starting tomorrow. They would be on vacation for the next week and a half!

“I can’t wait,” Hiro said. “I hope Ms. Smith doesn’t assign something hard today.”

“I hope she does,” Caleb grinned. “My favorite thing is a math challenge.”

“Good afternoon, class!” Ms. Smith called. “I know you’re excited to start your vacation. So we’re doing something fun today.”

“Yes!” Hiro cheered.

“Have you enjoyed taking care of Dorothy?” Ms. Smith asked. The class nodded.

Dorothy was the new class hamster. The students named her after Dorothy Johnson Vaughan. Dorothy Johnson Vaughn was Ms. Smith’s favorite mathematician. Dorothy’s cage sat on a cabinet. The cabinet held all her supplies. 

“I’ve found a pet sitter who can care for Dorothy all 12 days of the break,” Ms. Smith said. “I want him to have everything he’ll need during that time. So you’re going to help me plan my trip to the pet store.”

Ms. Smith drew four columns on the board. She labeled them Food, Treats, Bedding, and Chew Toys.

Illustrations by David SanAngelo

“We’ll split into four groups,” she explained. “Each team will oversee one of these elements of Dorothy’s care. You need to find whether she has enough supplies to last 12 days or if I’ll need to buy more.”

Ms. Smith assigned students to each group and wrote their names on the board. Hiro ended up on the team in charge of food, along with Marcie and Ben.

“OK,” Ben said. “Let’s look in the cabinet and see how much food we’ve got.”

Hiro bent down to open the cabinet. On the bottom shelf, a clear container was filled with hamster food up to a line marked “1 cup.” An unopened bag of food sat next to it.

“Dorothy gets  cup of food every day,” Hiro said. “There should be 4 cups of food in this bag, so . . .” Hiro grabbed his notebook and did a few quick calculations. “Yes! She should have more than enough for
12 days!”

By the end of class, everyone had written their answers on the board. Caleb leaned over to ask Hiro, “How did it go?”

Hiro grinned. “Easy as hamster food!”

“We’ll split into four groups,” she explained. “Each team will work with one thing Dorothy needs. You need to find whether she has enough supplies to last 12 days or if I’ll need to buy more.”

Ms. Smith assigned students to each group. Then she wrote their names on the board. Hiro was on the team in charge of food. Marcie and Ben were his teammates.

“OK,” Ben said. “Let’s look in the cabinet and see how much food we’ve got.”

Hiro opened the cabinet. A clear container sat on the bottom shelf. It was filled with hamster food up to a line marked “1 cup.” An unopened bag of food sat next to it.

“Dorothy gets 1/3 cup of food every day,” Hiro said. “There should be 4 cups of food in this bag, so . . .” Hiro grabbed his notebook and did a few quick calculations. “Yes! She should have more than enough for 12 days!”

By the end of class, all of the students had written their answers on the board. Caleb leaned over to talk to Hiro. “How did it go?” he asked.

Hiro grinned. “Easy as hamster food!”

12 Days Later . . .

A week and a half flew by. Hiro and Caleb dropped into their seats in Ms. Smith’s class.

“Finally, back to math class!” Caleb rejoiced.

Ms. Smith stood in front of the class with a frown. “Thank you all again for helping me to stock Dorothy’s cabinet,” she said. “Unfortunately, I just got a call from her caretaker. He had to buy more food. There wasn’t enough after all.”

Hiro sank down in his seat. “Oh no,” he murmured. “I knew it seemed too easy . . .”

“Hold on,” Caleb said. “Can I take a look at your notebook?”

Hiro passed it over glumly. Caleb studied Hiro’s notes and the calculation he had made on the next page.

“Your math is correct,” Caleb stated. “The pet sitter should have had enough. Unless . . . ”

A week and a half flew by. Hiro and Caleb dropped into their seats in Ms. Smith’s class.

“Finally, back to math class!” Caleb said.

Ms. Smith stood in front of the class. She was frowning. “Thank you all again for helping me to stock Dorothy’s cabinet,” she said. “Unfortunately, I just got a call from the pet sitter. He had to buy more food. There wasn’t enough after all.”

Hiro sank down in his seat. “Oh no,” he murmured. “I knew it seemed too easy . . .”

“Hold on,” Caleb said. “Can I take a look at your notebook?”

Hiro passed his notebook to Caleb. Caleb studied Hiro’s notes and the calculation he had made on the next page.

“Your math is correct,” Caleb said. “The pet sitter should have had enough. Unless . . .”

Illustrations by David SanAngelo

Caleb raised his hand. “Ms. Smith, can we take a look in Dorothy’s cabinet?”

Caleb led Hiro, Marcie, and Ben over to the hamster supplies. The food in the clear container was gone, and the bag beside it was empty except for a few crumbs. Caleb lifted the bag, turning it all around to inspect it.

“Aha!” he exclaimed. “Here’s where the problem was.”

Caleb poked his finger through a hole in the bottom of the bag. The edges were ragged and chewed. “Looks like we have more furry friends in this classroom than just Dorothy!”

“Oh dear,” Ms. Smith gasped. “We’ll have to get more plastic containers if we’ve got a mouse on the loose!”

Caleb raised his hand. “Ms. Smith, can we take a look in Dorothy’s cabinet?”

Caleb led Hiro, Marcie, and Ben over to the hamster supplies. The food in the clear container was gone. The bag beside it was empty except for a few crumbs. Caleb lifted the bag. He turned it all around to inspect it.

“Aha!” he exclaimed. “Here’s where the problem was.”

Caleb poked his finger through a hole in the bottom of the bag. The edges were chewed. “Looks like we have more furry friends in this classroom than just Dorothy!”

“Oh dear,” Ms. Smith gasped. “We’ve got a mouse on the loose!”

Activities (7)
Answer Key (1)
Activities (7)
Answer Key (1)
Step-by-Step Lesson Plan

1.  SPARK ENGAGEMENT.

Before or after reading the article, spark a discussion based on the following questions.

  • What kinds of supplies do you need to take care of a pet? 
  • How often do you think that those supplies need to be replaced? 
  • Describe a real-life situation when you might need to divide one number by another.

2. INTRODUCE THE MATH CONCEPT AND VOCABULARY

  •  Imagine a pan of brownies. If we cut the pan into 6 equal pieces, what fraction would represent each one? (1/6)  
  • What operation did we use to split the pan into even parts? (division
  • Let’s say that we want to split each of the brownies in half. How many brownies would there be now? (12)  
  • In this situation, we divided a whole number by a unit fraction. Write or display the equation 6 ÷ 1/2 = 12. A tape diagram can help you visualize how this works. Draw or display a tape diagram with 6 wholes. Then split each whole into halves and write 1/2 within each half. 
  • Today we will divide whole numbers by unit fractions to solve a mystery.

3. WORK THROUGH THE “WHAT TO DO” BOX.

  • How much bedding was used each time Dorothy’s cage was cleaned? (1/2 bag
  • How many bags of bedding were there? (2 bags
  • What did we need to do to the equation before we could find the answer? (We needed to switch the operator, then flip the fraction.) 

4. REINFORCE WITH MATH PRACTICE.

Have students solve for how long Dorothy’s food should have lasted. 

Text-to-Speech