Youngsters from north Norfolk schools were sent out onto beaches to collect washed up plastics, as part of a national campaign to stop the problem.
The Norfolk Rivers Trust's education team worked with four schools on the project in the spring and summer terms to investigate microplastics in the environment.
More than 150 pupils, aged from seven to 10, were involved from Blakeney, Holt, Kelling and Walsingham primary schools.
They took part in five days of activities including a beach litter pick and a plastic sorting exercise, with samples sent for analysis.
The pupils were taught how to conduct a survey using scientific equipment as well as learning about water quality in rivers and seas and the importance of protecting the aquatic environment for the native wildlife and for human health and food production.
Norfolk Rivers Trust's Ursula Juta said: "The main find during the beach pick was polystyrene, and during the sorting activities we discussed ways to try and minimise the volume of plastic entering the environment, focusing on how best to eliminate its use altogether, as so little of it is actually recycled."
The project was carried out thanks to a grant from the Sheringham Shoal Community Fund.
Karl Butler, the power plant manager at the offshore wind farm, which is between nine and 17 miles off the coast of north Norfolk, said: "This is a highly topical project, and it is great that the grant has helped enlighten a large number of children in the community about the marine environment issues associated with plastic. I hope some of them will be encouraging their families to take action."
The national campaign, the Big Microplastics Survey, is managed by Just One Ocean and the University of Plymouth.
Many microplastics find their way into the sea from the waste water systems which feed into rivers.
Microplastics are defined as all forms of plastics less than 5mm in size. They can enter the oceans as beads or microfibres from clothes or from larger plastic items, such as drinks bottles.
The damage caused to the sea by plastics was highlighted by Sir David Attenborough in his Blue Planet II series.
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