Science Fair Prjojects

Science Fair Project Ideas
Science Fair Project Guides

Project Idea Topics



10 Winning Science Fair Projects That Will Make You Feel Dumb
7 Science Experiments That Changed the World


What Makes Bones Hard? Can You Make ‘Rubber’ Bones by Removing Minerals?

Background Research
Materials and Equipment
Experimental Procedure
Data Gathering
Grade Level:K-5th Grade
Time Required:Less than 1 week
Materials:Readily available


We know that our bodies are made of bones, our skeleton. But what makes our bones hard and tough enough to hold up our body weight? Every single person has a skeleton made up of many bones. These bones give your body structure, let you move in many ways, protect your internal organs, and more. Can we turn bone into rubber though? In this experiment, we will find out exactly how to turn a bone into a ‘rubber’ bone – one that can bend!

Background Research:

A lot of the time, when we see bones, it is in a museum, maybe on a dinosaur figure or in a display case. You might think then that your bones aren’t living – but that’s not true. The bones that make up your skeleton are all very much alive, growing and changing all the time like other parts of your body. Almost every bone in your body is made of the same materials:

  • The outer surface of bone is called the periosteum. It's a thin, dense membrane that contains nerves and blood vessels that nourish the bone.
  • The next layer is made up of compact bone. This part is smooth and very hard. It's the part you see when you look at a skeleton.
  • Within the compact bone are many layers of cancellous bone, which looks a bit like a sponge. Cancellous bone is not quite as hard as compact bone, but it is still very strong.
  • In many bones, the cancellous bone protects the innermost part of the bone, the bone marrow. Bone marrow is sort of like a thick jelly, and its job is to make blood cells.
  • When you were a baby, you had small hands, small feet, and small everything! Slowly, as you grew older, everything becomes a bit bigger, including your bones.
  • A baby's body has about 300 bones at birth. These eventually grow together to form the 206 bones that adults have. Some of a baby's bones are made entirely of a special material called cartilage. Other bones in a baby are partly made of cartilage. This cartilage is soft and flexible. During childhood, as you are growing, the cartilage grows and is slowly replaced by bone, with help from calcium.
  • By the time you are about 25, this process is complete. After this happens, you can't grow any more — the bones are as big as they will ever be. All of these bones make up a skeleton that is both very strong and very light.
  • Vinegar affects bone density on a couple of ways. First off is that it makes otherwise "insoluble" calcium soluble. That makes it able to be absorbed by the body. This can be witnessed in the old high school experiment where you dissolve eggshells in vinegar. Once paired with vinegar, calcium is absorbed and able to be utilized by bone.
  • A second, lesser known reason, is that the main acid in vinegar, acetic acid, lowers the amount of phosphorus the body can absorb. Phosphorus is a strong acid from meats and beans and grains unlike the weak acid of vinegar.


It is possible to turn a regular chicken bone in to a ‘rubber’ bendable bone.

Materials and Equipment:

  • Chicken bones
  • Large jar
  • White Vinegar

View the rest of What Makes Bones Hard? Can You Make ‘Rubber’ Bones by Removing Minerals?


Copyright © 2002-2009, All Rights Reserved.