Why did the writer use the dash in front of the preposition "from"?
One summer a teenager I knew, a young man who had the highest IQ ever recorded by the local school system, repainted a neighbor’s roof. He climbed up with his paint bucket and roller and started to paint ― from the bottom to the top. When he got to the highest point of the roof, he realized he was in trouble. On the way down, he slipped on the fresh paint, fell off the roof, and broke his leg. He was very good at math and reading, but he couldn’t think of the idea of starting from the top.

― from the bottom to the top.

Why did the writer use the dash in front of the preposition "from"?

Please help me!
Thanks!

Question

Why did the writer use the dash in front of the preposition "from"?
One summer a teenager I knew, a young man who had the highest IQ ever recorded by the local school system, repainted a neighbor’s roof. He climbed up with his paint bucket and roller and started to paint ― from the bottom to the top. When he got to the highest point of the roof, he realized he was in trouble. On the way down, he slipped on the fresh paint, fell off the roof, and broke his leg. He was very good at math and reading, but he couldn’t think of the idea of starting from the top.

― from the bottom to the top.

Why did the writer use the dash in front of the preposition "from"?

Please help me!
Thanks!

Answer

A dash here can indicate surprise. When it is used that way, it would not be unusual for the sentence to end with an exclamation point (!). Also, in general, when reading aloud, a dash means a long pause used for emphasis.

In this case, the writer is emphasizing the mistake. "He is painting a roof, and of course a smart person like him should know that he had to paint from the top to the bottom--but he painted it from the bottom to the top!"

Here are some other examples.

I thought it was going to rain--but it snowed.

"He knew the model boy very well though—and loathed him." "Tom Sawyer," by Mark Twain.

Answer

It's a way to indicate a pause, to cue the listener/reader to wait for the punch line, or significant line of the story. The teenager was supposed to be extremely intelligent, but he didn't display common sense when he painted the roof and got stuck at the top of the roof and couldn't get down without stepping on the area he had already painted. I can't quite envision what kind of roof he was painting though, because if you start at the bottom of my roof, when you reach the peak you would just go down the other side, unless the point is that he'd have to have someone else move the ladder for him. He still wouldn't be stuck at the top.