More classroom supplies were dumped outside an Upper West Side public school last week, three days after the city Department of Education promised the inexcusable waste would stop.

Recycling advocate Anna Sacks found bags outside PS 166 the Richard Rodgers School of Art & Technology with stacks of multi-colored construction paper, an opened but full cannister of “Wet Ones” wipes, a book by beloved kids’ author Arnold Lobel, “Grasshopper on the Road,” games, wooden rulers, and a bag stuffed with children’s clothes.

“This is what I saw in their trash on Tuesday, three days after the NY Post article about their unnecessary waste of school supplies, “ Sacks wrote on her Instagram page, @thetrashwalker.

Some items were apparently left by a summer camp program run at the school by a non-profit, Roads to Success, including a new-looking blue and yellow T-shirt marked “Kids Creative & Roads to Success.”

“It’s disappointing,” Sacks said. “It’s supposed to be a ‘zero waste school’ focused on reducing, reusing and diverting.”

The leftovers outside the West 89th Street campus are just one example of a “massive problem,” said Sacks, who lives nearby.

The Post reported last Sunday that Sacks found a trove of supplies such as books, crayons and markers, some new and still in original packaging, outside PS 166 and nearby PS 133 Manhattan School for Children.

After alerting the principal, she returned twice to find more usable items, including books, markers, hand sanitizer and sticky notes.

In response, the Department of Education Danielle Filson had said, “It won’t happen again.”