Okay kiddo, let me tell you a story about the Mississauga train derailment that happened in 1979. It was a really big accident that happened when a train was carrying dangerous chemicals and it went off the track.
So imagine you are playing with your toy train set, and one of your trains starts to go off the track. But instead of just falling over, this train is carrying some really harmful chemicals like propane gas. These chemicals are dangerous because if they get released into the air, they can cause bad things to happen to the people and environment around them.
So when the train in Mississauga derailed, it caused some of the propane gas to escape and start to spread around the area. People who lived nearby had to be evacuated from their homes and schools had to close down. It was really scary and a lot of people were worried about what might happen next.
But luckily, some skilled people were able to work together and contain the spread of the propane gas. They did things like spraying water to keep it from spreading farther and making sure people stayed away from the danger zone.
Overall, it was a really unfortunate accident, but people learned a lot from it and now take extra precautions when transporting dangerous materials. It reminds us that we should always be careful and look out for potential dangers, even when we're playing with toy trains.