On China’s e-commerce platforms, there is a booming new market for some seriously unusual items, from empty milk cartons to used pen refills.

This thriving trade in plastic junk is being fueled by Chinese parents, who try to help their children complete their schools’ recycling projects — even though many are voluntary.

But these projects are sometimes harsh and inflexible. In some cases, schools are ordering each student to collect dozens, or even hundreds of items of used plastic every month. If they fail, it may affect their grades — and possibly their teacher’s performance assessment, too.

The result is a system that is putting families under continual pressure to source large amounts of recyclables. Busy parents often find themselves falling behind on their plastic quotas — and bulk-buying waste online to make up the shortfall.

Recycling waste has become one of the most popular product categories on major Chinese e-commerce platforms in recent months, according to domestic media reports.

On Alibaba’s secondhand trading app Xianyu, there are now hundreds of vendors selling milk cartons, pen refills, old cardboard boxes, and many other used items.

A stack of 100 empty milk cartons, rinsed and dried for recycling, typically sells for around 30 yuan ($4). Bundles of 100 used pen refills are priced at around 20 yuan. For many parents, it’s well worth the cost.

Zhang Yunping, the mother of an elementary school student based in eastern China’s Zhejiang province, is a regular buyer of recycling waste. She said her child’s school often requires each student to hand in 100 milk cartons a month.

“If we can’t collect enough, I buy some online because it’s more convenient,” the 37-year-old told Sixth Tone. “The number of milk cartons is linked to my child’s grades, so we try to collect as many as possible.”

And the environmental awareness assignments don’t end there. Zhang said the school sometimes also tells students to make clothes out of old newspapers or plastic bags.

Lin Ya, a 33-year-old elementary school teacher based in Shanghai, said that some schools have set quotas for collecting recycling waste, and now partially assess teachers’ performance based on their ability to meet those quotas.

“This puts a lot of pressure on teachers,” said Lin. “It’s also difficult for children who don’t like having to drink milk to complete the tasks.”

The surge in demand for plastic waste has amazed users on Chinese social media, many of whom were unaware of these school recycling quotas. The topic “Who’s buying empty cartons and pen refills” has received millions of views on the microblogging platform Weibo.

Most commenters reacted by criticizing schools for setting such burdensome and inflexible assignments. Many argue parents often don’t have time for this kind of project, as they are already under a lot of pressure at work.

Opposition to this kind of mandatory homework assignment appears to be growing in China. In a commentary, the state-backed media outlet Guangming Daily said that schools should use more practical and effective methods to teach kids about the benefits of recycling, such as having students record a green trip and discouraging them from using disposable chopsticks when ordering takeout.

“Instead of assessing environmental assignments by counting how many milk cartons, pen refills, or bottles are collected, schools should consider giving children the freedom to choose their own topics,” the article read. “This approach encourages them to actively think about and discover environmental tips and events in their daily lives.”

China’s education authorities have previously tried to address the issue of unreasonable homework assignments. In 2021, the Ministry of Education issued a notice stating that schools should avoid setting low-quality homework that deviates from its intended purpose.

(Header image: Empty milk cartons and used pen refills for sale on Chinese e-commerce platforms. From Weibo)