How it works
In Millbrook, a made-up town, one person's spending is another person's wages: families spend at shops, shops pay helpers, and helpers spend again.
In 1929 a huge crash in the share market worried people, so families saved every coin. Shops sold less and needed fewer helpers, and the spiral turned down.
This happened around the world in the 1930s and is called the Great Depression. In some countries about one worker in every four had no job, and it lasted for years.
Neighbors shared and swapped. Slowly, governments paid people to build roads, bridges and schools, so wages meant spending and spending meant jobs again.