This lack may arise because talk about systems requires advanced verbal skills. It has been widely assumed that children's vocabularies do not approach this level of sophistication until early adolescence. The researchers found it possible to developed a technique that allowed them to study the complexity of children's non-verbal concepts of environmental systems. Pictures and computer simulations of environmental problem situations were used to minimise demands on children's language skills. This technique then formed the basis for a series of trials involving children of different ages in several European countries.
Many environmental terms are likely to be unfamiliar to children.
Both older and younger children can readily suggest remedies to environmental problems. They also tend to offer solutions that emphasise the importance of processes rather than resources. Younger children tend to see fewer negative outcomes arising from an intervention to improve the environment. This is presumably because they do not consider all of the consequences of an intervention. Younger children sometimes offer more complex solutions to environmental problems than older children.