"TK Maxx wanted to bring local children closer to nature," said a rep of the area with a sundial and 12 two-seater chairs near the remains of a Neolithic hut.
Woodland Trust threw a competition for Elmstead Primary School kids. The winning design will be built in the charity's new 10ha wood at Elmstead Market, near Colchester.
A chainsaw artist is carving the sun-dial at the centre of the outdoor classroom, for which the youngsters helped plant some of the 1,500 perimeter hedge plants.
TK Maxx is funding over 1ha of woodland after raising tens of thousands of pounds by charging customers for plastic bags.
John Brown, a Woodland Trust manager, said: "We want children to develop a life-long affection for woodland, vital to realise our long-term vision of doubling native woodland cover in the UK."
Jo Murphy, head of customer relations at TK Maxx, said: "This is part of our commitment to local communities and an environment strategy to preserve native woods."
Subscribe to Horticulture Week for more news, more in-depth features and more technical and market info.