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Grade 8: Science with Mrs. Chen

Eighth graders in Mrs. Chen’s science class learned about density (the ratio of a substance’s mass to its volume) and how density determines whether an object will sink or float before engaging in a wet and sometimes wild lab experiment. 
Their goal was to sink a “submarine,” anchor it underwater for a period of time, and then cause it to rise to the surface again. The submarine was an empty film canister with a hole in the lid.
 
Using other materials including a graduated cylinder, tap water, pennies and Efferdent tablets, scientists got to work trying different combinations of variables: the amount of water in the canister, the number of pennies used to weigh it down, and the position of the canister - lid right side up or upside down. As they tested their theories, each team recorded the data and results; when they found a combination that worked, they attempted to replicate it. 
 
Rowan Brown and Hayden Caulkins had a bit of a struggle getting their variables to work together for the desired outcome. “We can’t find the balance between floating and sinking,” said Rowan. Their canister either sank or floated, so they tried manipulating the Efferdent tablet to affect the density of the water.
 
Across the room, Sama Abdulmeer said, “It’s a challenge to keep the measurements the same every time.” She and her lab partner, Lydia Drake, tackled Mrs. Chen’s “extra extra challenge” -- getting the submarine to reliably stay on the bottom of the cylinder for exactly 15 seconds. 
 
As Mrs. Chen circulated around the room to verify understanding and help students troubleshoot, she enjoyed observing the students while they tackled their first inquiry lab of the year. By replacing a prescribed procedure with an open-ended challenge, inquiry labs promote curiosity and allow students to practice collaboration and problem-solving skills. She noted how impressed she was by the range of creative approaches attempted by students.
 
For homework, scientists answered lab questions that allowed them to reflect on the lesson and their experiments:
  1. Why did the gas from the tablet help the canister rise to the surface?
  2. How can you relate this experiment to how a real submarine works?
  3. Would an object float better or worse in salt water compared to fresh water? Why?
  4. Explain the science behind this lab. How does the mini-submarine work?

Learn more about Mrs. Chen!
 
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Graland Country Day School

Graland Country Day School is a private school in Denver, Colorado, serving students in preschool, kindergarten, elementary, and middle school. Founded in Denver in 1924, Graland incorporates a rich, experiential learning approach in a traditional classroom setting, emphasizing the development of globally and socially conscious leaders who excel academically.