Knotted Bones Science Experiment November 17 2009

Want to tie some bones into knots?

You may have to cook a turkey before Thanksgiving and bring the bones to class if you'd like to try this experiment. Or, use poultry bones of any kind and ask for donations from families or a local butcher shop. Make sure you have enough so that each student can take home a knotted bone; if that's not possible or if you decide to do this experiment as a demonstration, consider sending home a sheet of directions for kids to make their own during their Thanksgiving weekend!

The theory behind the experiment is fairly simple. Bones are made of the same stuff as eggshells, which is calcium carbonate. When soaked in vinegar, the calcium carbonate of the bone reacts chemically and releases carbon dioxide. This will cause the vinegar to bubble.

To make this a little more interesting, I set up the sheet so that different bones are soaked in 3 different liquids - vinegar, water, and one of choice. I think it might be interesting to use soda to see how it compares with the other two.

After a day, the bones are supposed to be soft enough so that students can tie them into knots. When the bones sit out in the air (after they're tied), they harden again. How? They take the carbon dioxide back from the air.


poultry bones
cups deep enough to soak the bones, a set for each student
a third liquid

The Scientific Process

The Turkey Science - Knotted Bones Sheet is set up to take your students through the steps of the Scientific Process.

Question: Which liquid will soften turkey bones so that they can be tied in a knot?

Hypothesis: Have students write down a guess - the water, vinegar or third option.

Procedure: Write this on the whiteboard, chart paper or overhead with the students.

  1. Use three cups of equal size, and write your name on the outside of each one with permanent marker.
  2. Fill each cup with three different liquids: one with vinegar, one with water, and one with a liquid of your choice.
  3. Put a poultry bone (or two) in each cup and leave overnight.
  4. The next day, which liquid allows you to tie the bones in a knot? What results did you get with the liquid of your choice?

Observations: These are set up for sketches or sentences. Use them at any point during the experiment.

Results: Write down what happened to the bones in each of the cups.

Conclusion: This basically answers the question.

After the conclusion, you might want to add "The Next Question" - What will happen to the knotted bones if left out on my desk overnight?

Random Turkey Facts

  • A male turkey is called a Tom, a female is called a Hen, and a baby turkey is called a Poult.
  • Turkey is the only native poultry breed in the Western Hemisphere.
  • Turkeys don't have ears, but have excellent hearing and see in color.
  • Wild turkeys can fly as fast as 55 miles per hour over short distances.
  • The wattle is what hangs from a turkey's chin!
  • Tryptophan, a hormone that makes you sleepy, is naturally found in turkey. Even though turkeys are blamed for making us sleepy, scientists say that in fact it's probably all of the other heavy-carbohydrate food we eat during the Thanksgiving meal.
  • Turkeys can drown if they look up for extended periods of time when it's raining, and have been known to have heart attacks.

    (Thanks to Kid Zone and Thanksgiving World!)