Resource 1: Misconceptions surround States of Matter

Background information / subject knowledge for teacher


Children find it very difficult to understand just how small atoms and molecules actually are. A common misconception is that cells and atoms are comparable; in fact cells contain millions of molecules.

One way of introducing the idea of ‘magnitude’ is to use a football. If you measure the diameter of a football and divide it by 108, that gives the size of an atom. If you multiply it by 108, that gives the size of the Earth. If you have access to the internet, there is a website called ‘powers of ten’ which will help you to envisage the magnitude of atoms: primer/ java/ scienceopticsu/ powersof10/ [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .

Children also have misconceptions about the particle model for matter. Some of the common ones that you will find include:

  • If a solid or liquid is heated, the particles get bigger. This is not the case. At higher temperatures, they move about more and take up more space, but they do not get bigger.
  • Children tend to overestimate the space between the particles in liquids. They regard a liquid as half-way between a solid and a gas. This is not the case. The particles in a liquid are close together, although they are free to move and change place.
  • Children confuse ‘melting’ and ‘dissolving’. Some children think that when a solid melts, the particles ‘pop’ or simply disappear.
  • Children find it difficult to accept that most of a gas is empty space.
  • Children assume that the particles will have the same properties as the solid, liquid or gas they make up and therefore will explode, contract, expand or change shape.
  • When they see a diagram of a molecule such as oxygen (O2), children think it must be a compound because there are two atoms joined together. They do not always understand that if both the particles are the same then it is an element.

3. Making revision fun

Resource 2: Think-pair-share Activity