Changes in Matter - It's the Law

Nature's laws are different than the government's laws. Nature's laws are scientific ideas that have proven to be true over and over again. There is a law of science that applies to matter. It is called "The Law of Conservation of Matter". This law says that matter cannot be created or destroyed by ordinary means.

Look at your computer. It has many pieces. Pretend that you weigh your computer and find that it weighs five kilograms. Now, pretend that you use a sledge hammer to destroy your computer. CRASH! BANG! SMASH! What happens? Computer pieces fly everywhere. The keyboard buttons pop off, the computer screen shatters; wires poke out from the hard drive. You have certainly destroyed the computer. But, have you destroyed the matter that makes the computer?

Imagine now that you collect all the pieces of the destroyed computer and weigh them. What will the weight be? Five kilograms - exactly what it was before you destroyed the computer. Though you destroyed the computer and changed the shapes and sizes of its parts, you did not destroy matter. Matter can be neither created nor destroyed. Remember, it's the law!

The weight of the reactants =
The total weight of the products!

Try it!


  • Scale
  • 25 Lego® pieces


  1. Take one Lego® block and measure the mass in grams. Record your measurement in the data table. Predict the total mass of all the Lego® pieces.
  2. Take 25 Lego® blocks and pile them up on the balance and measure the mass in grams.
  3. Now construct a solid block of Lego®s and measure the mass in grams.
  4. Take the block apart and re-assemble it into 2 different shapes, then measure their total mass in grams.
  5. What conclusion can you make about the mass of all the single pieces compared to the mass of the pile, or the mass of the block, or the mass of the 2 shapes?


Number of Lego® pieces Mass in grams



Predict the mass of all the Lego®s you are using


Lego® pile (all 25 pieces on the scale together)


Lego® block (all 25 pieces put into a block shape)


2 Lego® shapes (measure the mass of both at the same time)



You're the scientist!

Matter cannot be created nor destroyed but it can certainly be changed.


What happens to the weight of matter when it is broken?


Write down your answer.


  • One piece of hard candy such as a butterscotch or peppermint
  • Scale
  • Paper towel


  1. Weigh the candy.
  2. Wrap the candy in the paper towel and with the help of an adult, smash the piece of candy.
  3. Place all of the small pieces on the scale and weigh them.
  4. Compare the weight of the whole piece of candy to the sum of all the pieces.

What happens to the weight of matter when it is broken?


Record your findings.


Was your hypothesis correct? Write down your answer.

utah state board of education This Sci-ber Text was developed by the Utah State Board of Education and Utah educators.