And in the interest of fairness, Father's Day, too.
Students at Rodeph Sholom Day School on the Upper West Side, where tennis legend John McEnroe sends his children, came home Friday with an unusual note tucked into their book bags.
"I am writing this letter to inform you that after much thought and discussion this past year, we will not be celebrating Mother's Day and Father's Day," began the letter written by Cindi Samson, director of the school's lower elementary division.
"At this time, these holidays are not needed to enhance our writing and arts programs," the letter continued. "Second, families in our society are now diverse and varied.
"We are a school with many different family makeups, and we need to recognize the emotional well-being of all the children in our school. Holidays that serve no educational purpose and are not vital to the children's education need to be evaluated in terms of their importance in a school setting, as the recognition of these holidays in a social setting may not be a positive experience for all children."
When did the biblical commandment--"Honor thy father and thy mother"--become a threat to children's emotional well-being?
Said one outraged mother: "There are ways of showing sensitivity to the needs of children in unusual situations that don't require undermining traditional family structures.
"This is an inappropriate and politically correct response," said the mom, who asked not to be identified.
Rodeph Sholom, affiliated with a Reform Jewish synagogue, educates kids from age 2 through sixth grade. Tuition runs around $15,000 a year for pre-kindergarten, and just under $20,000 for grade 6.
The bans affect kids ages 4 and older; younger kids apparently are still permitted to celebrate Mother's Day, which is this coming Sunday. And Father's Day, which is June 17.
Last Mother's Day, kids made cards for their mommies. For Father's Day, they decorated soup cans for their dads to use as pen holders.
That ended last week, a parent said, when a man - who adopted his son with a male partner - boasted that he had persuaded administrators to remove Mother's Day from the school's holiday list.
Reached at school yesterday, Samson said the decision to cancel was not based on a single case.
"The reasoning was several-fold," Samson said. "One is, it didn't serve an academic and educational need. Number two, families are changing. Some children were very uncomfortable."
She pointed out that some kids have one parent. Or, "There may be two fathers, two mothers, the mother may not have custody, it could be a grandmother."
The school's headmaster, Irwin Schlachter, did not return a call.
One disappointed mother found the ban puzzling.
"I thought it was sweet that they spend some time thinking about their parents, making a little art project," said the mom, who suggested that kids without moms or dads make gifts for their grandparents.
Like most parents I interviewed, she feared speaking out would adversely affect her child, and asked not to be identified.
I'm not sure what's more fuzzy-headed: preventing kids from honoring their parents or believing that banning a celebration will somehow help kids who are not part of traditional families.
Kids don't live in a bubble. Not even on the Upper West Side.