Sometimes it doesn't matter how many times you tell someone that a surface is hot. They're just going to have to touch it.
In my first math lesson with my new classes this week, I noticed a trend in my first couple of classes. As they worked on their homework near the end of class, several of them got to a particular problem and didn't know what to do. It had three different variables and they were supposed to evaluate it.
Without exception, those who asked had neglected to read the instructions, where it gave a value for each variable.
I figured I'd save myself a little trouble and warn my remaining class periods. A part of the lesson had the exact same type of problem, so when we got to that, I mentioned the issue. I told them that other students got to those problems in the homework and didn't know what to do because they didn't read the directions.
Later, we get to homework time. I walk around the room, helping students when they get stuck.
Invariably, more than one raises their hand. "I don't know what to do here."
I point to a line in their textbook. "Did you see this?"
"No, I—oh! You totally warned us and I did it anyway!"
They felt like idiots. I assured them they weren't the only one to do it, and made a little joke about how they'd never forget to read directions again, right?
I already know there's only so much they can absorb at one time, and which parts stick depends on their own priorities.
Live and learn, kiddos.