The stock market is a vary visible example of how ‘market prices’ change as events in the world change. Steps:
1.) Pick a company that is of interest to you, and then Google ‘What is the price of (stock name)’.
2.) What is the price today? Expand the graph to show 6 months, 1 year, or 5 years.
3.) What has happened to the price of stock over that time period? Do you know, or can you imagine, events in the world that led to changes in the price of the stock? What might be of those ‘events’ be?