STANDARDS

CCSS: 3.MD.A.1

TEKS: 3.7C

DynaMath Mystery: The Case of the Suspicious Sleepover

Caleb Craft is in fifth grade. He’s 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. 

Illustrations by David SanAngelo

“Rise and shine, kids!” Mr. Craft called.

Caleb woke with a big yawn. He was in a sleeping bag on his bedroom floor, next to his friends Jo, Hiro, and Luis. Everyone had come over last night for a sleepover.

“Looks like you guys had a bit of a rowdy night,” Mr. Craft chuckled.

Caleb frowned. “What do you mean? We watched a movie.”

“Come see for yourself.”

Everyone got up to follow Mr. Craft downstairs to the living room. Their eyes widened.

“What happened?” Hiro gasped.

There had been a framed family photo on a table. Now it was on the ground—the glass was shattered!

“It’s all right,” Mr. Craft said. “We can replace the frame. But something must have knocked it over.”

“I don’t remember that picture falling,” said Jo. No one else remembered either.

“So none of us know how it happened?” Caleb asked. “Hmm. This sounds like a case to solve! And I know just where to start. Everyone, come back upstairs with me!”

The group sat in a circle in Caleb’s bedroom.

“We’re going to re-create our schedules from last night,” Caleb announced. “I was the first one in bed—I was asleep by 8:00 p.m. Luis, how about you?”

“I was up late,” Luis said. “I went to sleep at 8:40 p.m.”

“Great!” Caleb said. “What did you do between 8:00 p.m. and 8:40 p.m, and who did you see?”

“Wake up, kids!” Mr. Craft called.

Caleb woke up. He yawned. He was in a sleeping bag on his bedroom floor. His friends Jo, Hiro, and Luis were next to him. Everyone had come over last night for a sleepover.

“Looks like you guys had a rowdy night,” Mr. Craft said.

Caleb frowned. “What do you mean? We watched a movie.”

“Come see for yourself.”

Everyone got up. They followed Mr. Craft downstairs to the living room. Their eyes widened.

“What happened?” Hiro gasped.

There had been a family photo on a table. It was in a nice frame. Now the photo was on the ground. The glass was shattered!

“It’s all right,” Mr. Craft said. “We can replace the frame. But something must have knocked it over.”

“I don’t remember that picture falling,” said Jo. No one else remembered either.

“So none of us know how it happened?” Caleb asked. “Hmm. This sounds like a case to solve! And I know where to start. Everyone, come back upstairs with me!”

The group went back to Caleb’s bedroom. They sat in a circle.

“We’re going to re-create our schedules from last night,” Caleb announced. “I was the first one in bed. I was asleep by 8:00 p.m. When did you go to sleep, Luis?”

“I was up late,” Luis said. “I went to sleep at 8:40 p.m.”

“Great!” Caleb said. “What did you do between 8:00 p.m. and 8:40 p.m.? Who did you see?”

Illustrations by David SanAngelo

“I didn’t see anyone. I was too focused on reading.” He held up a worn copy of Amulet: The Stonekeeper.

“That’s OK,” Caleb nodded. “When did you start reading?”

“I’m not sure,” Luis said. “I read for about 30 minutes. I do remember that when I started, Hiro was just about to go downstairs to take a phone call.”

Everyone turned to Hiro.

“That’s right,” Hiro nodded. “My dad called last night, and I went to the living room so I wouldn’t wake you up, Caleb.” He picked up his phone, scrolled through it, and then passed it around. “See? It says that it was 8:10 p.m. when he called. I remember seeing Jo coming back upstairs on my way there.”

Jo nodded. “I was coming from the kitchen. I went to get a glass of water.”

“What time was that?” Caleb asked.

“Well,” Jo thought, “I went upstairs at 8:00 p.m. Then I was in the bathroom for 5 minutes. I was probably in the kitchen for about 5 minutes too. After that, I went straight upstairs to bed.”

Caleb turned back to Hiro. “The picture was still on the table when you took your call?”

“Yes,” Hiro nodded. “Everything was normal. I spent about 10 minutes talking to my dad, then I came upstairs. You and Jo were asleep, and Luis was still reading.”

“Hmmm,” Caleb pondered. “It doesn’t seem like anything suspicious happened. And Hiro, it sounds like you were the last person who was downstairs last night.”

I didn’t see anyone. I was reading.” Luis held up a book. The book’s title was Amulet: The Stonekeeper.

“That’s OK,” Caleb said. “When did you start reading?”

“I’m not sure,” Luis said. “I read for about 30 minutes. I do remember one thing. Hiro went downstairs when I started to read. He was going to take a phone call.”

Everyone turned to Hiro.

“That’s right,” Hiro said. “My dad called last night. I went to the living room. I didn’t want to wake Caleb up.” Hiro picked up his phone. He scrolled through it. Then he passed it around. “See? It says that it was 8:10 p.m. when my dad called. I saw Jo coming back upstairs on my way to the living room.”

Jo nodded. “I was coming from the kitchen. I went to get a glass of water.”

“What time was that?” Caleb asked.

“Well,” Jo thought, “I went upstairs at 8:00 p.m. Then I was in the bathroom for 5 minutes. I was in the kitchen for about 5 minutes too. I went upstairs to bed after that.”

Caleb turned back to Hiro. “The picture was still on the table when you took your call?”

“Yes,” Hiro said. “Everything was normal. I spent about 10 minutes talking to my dad. Then I came upstairs. You and Jo were asleep then. Luis was still reading.”

“Hmmm,” Caleb said. “It doesn’t seem like anything suspicious happened. And it sounds like Hiro was the last person who was downstairs last night.”

Illustrations by David SanAngelo

“Oh!” Luis gasped. “I do remember one thing. Right after I went to bed, I thought I heard a crash. It woke me up! I thought I was dreaming, but could it have been the picture?”

Caleb leaned forward. “Do you know what time that was?”

“I looked at the clock,” Luis said. “I remember I had been sleeping for only about 15 minutes.”

Caleb sat back again, defeated. “That’s even stranger.”

Suddenly, a meow came from the door. Everyone jumped.

“Don’t worry,” Caleb said. “That’s just Whiskers. She's usually outside at this time . . .  That’s it!”

Caleb lifted Whiskers into his arms and darted down the stairs. Confused, everyone
else followed.

“Dad, you let Whiskers out last night, didn’t you?” Caleb asked.

Mr. Craft turned to him with a bewildered expression. “Yes, I did. Right before your friends arrived. But how is she inside?”

“What else did you do last night?” Caleb asked.

“I read for a while, then I took out the trash and went to bed,” Mr. Craft mused.

“What time was that?” Hiro chimed in.

“Oh!” Luis gasped. “I do remember one thing. I thought I heard a crash right after I went to bed. It woke me up! I thought I was dreaming. Could it have been the picture?”

Caleb leaned forward. “Do you know what time that was?”

“I looked at the clock,” Luis said. “I remember I had been sleeping for about 15 minutes.”

Caleb sat back again. He looked defeated. “That’s even stranger.”

A meow came from the door. Everyone jumped.

“Don’t worry,” Caleb said. “That’s just Whiskers. She's usually outside at this time of the morning. That’s it!”

Caleb lifted Whiskers into his arms. He darted down the stairs. Everyone was confused. They followed Caleb downstairs.

“Dad, did you let Whiskers out last night?” Caleb asked.

Mr. Craft turned to Caleb. He looked startled. “Yes, I did. I let her outside before your friends arrived. But how is she inside now?”

“What else did you do last night?” Caleb asked.

“I read for a while. Then I took out the trash and went to bed,” Mr. Craft said.

“What time was that?” Hiro asked.

Illustrations by David SanAngelo

“I went to bed around
 9:00 p.m. I took the trash out about 5 minutes before that.”

 “Aha!” Caleb grinned. “Mystery solved!” He strode over to the living room table and crouched down beneath it.
He pulled out a tiny mouse-shaped toy.

“Whiskers’s new catnip toy?” Mr. Craft asked.

“Exactly!” Caleb said. “She must have snuck back in when you opened the door to take out the trash. Playing with her toy got her excited, so she jumped up on the table and knocked the frame over! The timing checks out perfectly!”

“I went to bed around 9:00 p.m. I took the trash out about 5 minutes before that.”

 “Aha!” Caleb grinned. “Mystery solved!” Caleb walked over to the living room table. He bent down. He reached beneath the table.

Caleb pulled out a tiny toy. It was shaped like a mouse.

“Whiskers’s new catnip toy?” Mr. Craft asked.

“Exactly!” Caleb said. “Whiskers must have snuck back in when you opened the door to take out the trash. She played with her toy. She got excited. So she jumped up on the table. She must have knocked the frame over! The timing fits!”

Elapsed time

<p>The amount of time that has passed between the start and end of an event</p> <p><b>Example: </b>Jose started his math test at 1:15 p.m. He finished it at 2:05 p.m. Fifty minutes of time elapsed between when he started and finished his test.<br> </p>

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