October Book of the Month

Cao Chong Weighs an Elephant by Songju Ma Daemicke

Big picture

About the Book

This is the true story of a boy, Cao Chong, who lived in China more than 1,000 years ago! Cao's father, the emperor, was given an elephant as a gift. They had never seen a creature like the huge elephant and wondered how much it weighed. All the advisors in the country were challenged to find an answer to this question and they tried and tried with no success. Cao Chong had an idea! He used the principles of sinking and floating and some creative thinking to come up with a solution. Watch the video to see how he did it.
Why do ships float?

Students will listen to the book in their classrooms

The Challenge

Students should try the challenge at home!

Part 1--Experiment

You will need:

  • a cup
  • warm water
  • an egg
  • salt
  • a spoon


Big picture
  1. Fill the cup halfway with warm water. Place the egg in the cup. Does the egg sink or float?
  2. Carefully take the egg out. Add a spoonful of salt to the cup and stir until the salt dissolves. Put the egg back in gently. Does the egg sink or float? Has anything changed?
  3. Carefully take the egg out again. Add another spoonful of salt and stir until it dissolves. Put the egg back in. Does anything change as you add more salt?
  4. What is the difference between fresh water (water with no salt) and salt water? How does that difference affect whether the egg sinks or floats (the buoyancy of the egg)?

Part 2--Try Going Beyond the Egg!

1. After listening to how Cao Chong weighed the elephant and conducting the experiment, what do you wonder about?

2. Write down some I wonder questions. Think about using different objects, different liquids, or how you might weigh an object too large for your scale.

3. Be the scientist! Design and conduct an experiment to answer your favorite I Wonder question.

4. Show what you learned! Here are a few ideas:


  • Record a science TV show on your ipad or chromebook with props and take your audience through the experiment and the results of what you learned
  • Write and illustrate a book showing the experiment and the results of what you learned
  • Use any app you want that will show the progress of your experiment like a comic strip app, stop motion, or seesaw.

Turn in your product to Mrs. Wagner by Friday, October 18 so they can be displayed in the Learning Commons. If you have a digital product, bring your device to the library and Mrs. Wagner will help you share it