Extending the Particle Model of Matter Children’s Ideas

Below are common ideas children in grades K-6 have about this topic, compiled from research on children’s ideas about science. Consider what evidence might refute this idea, and why a child would be likely to believe this? Once you’ve entered all your answers you can click “printable page” at the bottom of this form to print your answers. You can also click “see possible response” for any question to see one possible response from the series content advisors.

1. Positively charged objects have gained protons rather than being deficient in electrons.

Children may not be aware of the electrical properties of subatomic particles at rest, i.e. that the electrons are negatively charged, protons positively charged, and nuclei neutral. For children and many adults the word “positive” also connotes a gain of something. However, when two different substances are rubbed together, one is always more likely to give some of the electrons from its surface to the surface of the other, leaving the former positively charged and the latter negatively charged. There is no movement of protons.

2. Electricity is a fluid that flows from one place to another.

Like some 18th century scientists, children may believe that electricity, like heat, is a kind of matter that flows. They may also be unaware of the difference between static electricity and electric current. In everyday language, electricity is a loosely used, catch-all term for both. In the more precise language of science, it might be defined as a form of energy generated by friction, induction, or chemical change that is caused by the presence of forces between the charged particles of which matter is composed. In static electricity, there is a one-time transfer of electrons from the surface of one substance to the surface of another, with no continuing “flow” of particles through the substance.

3. A charged object can only attract other charged objects.

Once they get used to the idea of unlike charges attracting and like charges repelling, children may be challenged by the idea that charged matter is also attracted to or repelled by neutral matter. When a negatively charged substance is brought near the surface of a neutral substance, the negative charges in the neutral surface are repelled away from the approaching surface, leaving behind the positively charged particles which are attracted to the approaching surface. The same process happens in reverse when a positively charged surface is brought near a neutral surface, but the net effect is the same – attraction.