"And the Stone Age became the Gravel Age, named after the long driveways of the time."
"The War of Roses took place in a garden."
"The Enola Gay dropped one tiny atom on Japan."
The Stone Age was a time where people discovered stone and used it to make tools and make things easier for them. It lasted over 2.5 million years. 
"And the Stone Age became the Gravel Age, named after the long driveways of the time."
The War of Roses was a war over the throne of England. It was fought between the Lancaster and York, and each had a symbol of a rose, but they were different colors.
"The War of Roses took place in a garden."
Enola Gay was a bomber plane that dropped the 1st atomic bomb on Japan during World War 2.  The bomb created lots of damage and killed thousands of people.
"The Enola Gay dropped one tiny atom on Japan."
The teacher explained the Stone Age by making it seem like it had to do with driveways and not the working to make tools and other things.
The way the teacher explains it makes it seem like it was a peaceful war in someone's garden rather than an actual war with Roses as their symbols.
Yeah in a garden...
The teacher explained Enola Gay to make it seem like the situation was not a serious thing and that nothing bad happened, but in reality, so many people died.