In this study we have interviewed eight teachers about when and how particle concepts should be taught. All of the surveyed teachers argue for an early introduction. This view is also consistent with the scientists on when the particle concepts should be introduced. By an early introduction teachers and scientists consider the age between 6-12 years old. A majority of the scientists and the surveyed teachers use concept of change as a entery point to talk about particle ideas. A substance that is commonly used among both teachers and scientists is water. We can also find out that the surveyed teachers think that the particle concepts are fundamental for pupils to get a broader understanding in school science learning.