The youngsters, aged between 7 and 11, have additionally been learning how to recycle paper.
A teaching assistant said the school was passionate about empowering the next generation of environmental campaigners.
"It has been exciting working with the children to look at how they can help make a positive impact on the environment," explained Maria Ashworth, adding some pupils were even changing "the ingrained normalities of adults" by encouraging changes at home.
"Multiple creatures in the sea have already died due to plastic and if we don't help them now they'll be extinct," said Myles.
"One of my favourite animals is turtles and they're getting killed because of plastic in the ocean... Some people just chuck everything everywhere and don't really listen."
"We've been talking about how we can make the school a better place for the animals," she said. "We can stop littering and maybe change the bins when they start overflowing."
Holly added: "Don't buy single-use plastic... If you can see the recycling symbol on the plastic then buy that and you can recycle it."