AMSTERDAM — “She hid Jews?”

Aleatha Hinds, 17, ventured a guess about Anne Frank’s identity as she waited in line for two hours recently to enter the museum devoted to that world-famous diarist, who hid with her family in a secret annex for 25 months during World War II.

“No, no, no!” replied several friends, all 11th and 12th graders from the St. Charles College high school in Ontario. “She was Jewish!” they corrected her, in unison.

“She was hiding in her father’s factory,” said Eric LeBreton, 16. “The Nazis were looking for all the Jewish people because Hitler was trying to do genocide.”

With attendance swelling to 1.3 million annually, from one million in 2010, the Anne Frank House has begun reckoning with a striking dimension of its popularity: Many of the younger and foreign visitors who flock here nonetheless have little knowledge of the Holocaust — and sometimes none about Frank. The museum and some others dedicated to Jewish life are seeking new ways to address a declining understanding of World War II and the genocide that took the lives of six million Jews in Europe, efforts that have increasing relevance as anti-Semitic incidents intensify across parts of Europe and the United States.