Sharon Regoli Ciferno, 50, a teacher at Charles A Huston Middle School in the US state of Pennsylvania, was with her daughter at a friend's house in Mexico on Monday when she sat on a deck ledge that doubled as a bench.
"She started laughing very hard and when she put her head back she lost her balance and fell back," her brother David Regoli was quoted as saying by the Fox News.
"She suffered multiple injuries to her body and brain," he said.
"Alcohol was not a factor. The building code standards in Mexico are not as stringent as in the US. Unfortunately, there was no back on the deck," her brother said.
The tragedy happened just as her students were getting ready to return to school from summer break.
Regoli Ciferno was married and a mother of two