Senses and ScienceAbility: Bones Inquiry

The purposes of this inquiry lab:

  • Discuss
    • Primary components of bone
    • Primary functions of skeleton
    • Consequences when calcium is lost from bone
  • Investigate
    • The change in mass of egg when calcium is removed from shell
    • What happens to bone when calcium is removed
    • Where blood cells are made in bone
    • What blood cells look like

In this laboratory experience, participants measured the mass of a chicken egg. The egg was placed in vinegar for 15 minutes. After 15 minutes, the chicken egg was dried and weighed. The change in mass was calculated.

While the participants were waiting for their egg to sit in the vinegar for 15 minutes,

  • They observed the skeleton and learned about the different kinds of bones.
  • They were able to compare chicken bones from which the calcium had been removed or reduced with chicken bones that had not had the calcium removed. The calcium was removed from the chicken bones by the same method as removing the calcium from the egg shell. They were soaked in vinegar.
  • They were able to test the bone marrow of chicken bones to detect the presence of blood, an indication that bone marrow is where blood cells are produced.
  • They were able to look in microscopes at prepared smears of blood cells.
  • Students were able to see eggs that had been fully demineralized, leaving only the membrane around the egg. 

  

These eggs have just been placed in vinegar. The bubbles are carbon dioxide gas that is produced as the vinegar reacts with the calcium (calcium carbonate) in the egg shell.  The picture on the right is a magnification of the picture on the left. This is what the students saw when they placed their eggs in the vinegar.

This egg has been in the vinegar for 24 hours.

  

These eggs were in vinegar for 48 hours. The shell is fully demineralized leaving only the underlying membrane. In the picture on the right, the membrane of one egg has been punctured. Lab participants were able to touch these eggs.

In this experiment, the mass of the chicken egg decreased due to the vinegar reacting with the calcium in the egg shell.  Just as calcium is important to the egg shell, calcium is important to bones. When there is not enough calcium in the bones, the bones become weak and are more likely to break.

The picture of the data chart below shows the data as measured, calculated, and recorded by the laboratory participants.

When engaging in the daily activities of life, we encounter “unexpected results” from time to time. The same is true in the lab. The same is true in these egg data results.  The starting masses of the eggs are fairly close. The changes in mass after being in vinegar are more variable and in a couple of cases unexpected.  These unexpected results could be due to our methodology, the equipment, or participant technique.  If you look carefully at the “change in mass” column, you may notice there are calculation errors.

We find in the laboratory that sometimes unexpected results happen and we cannot explain why. Most often, we will repeat the experiment or recheck our calculations and the unexpected will resolve. Sometimes, though, it is out of the unexpected that scientific discovery occurs!

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