A cheap roll of cardboard was a brilliant investment, says Sally Squires, nursery co-ordinator at James Peacock Nursery School in Ruddington, Nottingham.

One of our all-time nursery 'best buys' must be a £40 roll of corrugated cardboard that we used to create a castle complete with ramparts, dungeons and a fire-breathing dragon. We had a topic on fairy stories that really captured the children's imaginations, especially when we went to see 'Tangled' at the cinema. The children were taken by the idea of castles, the ramparts and drawbridges. Staff thought it would be perfect to create a castle because we felt that the home corners tended to be geared more towards girls and we wanted something that would also engage the boys' imaginations.

The card is a nice grey colour, so we didn't need to paint it. We turned plastic crawling tunnels on their end to make a base for the tower, and a climbing frame supports the walls and creates the ramparts for the children to climb up to and look out from. The dungeon at the bottom of the climbing frame is blacked out with material so that it's dark, scary and exciting. There are even skeletons in it! The children helped us to devise a pulley system for a drawbridge and they enjoy lowering and raising it.

Normally we do things like this for half a term, but almost a year on, the children are still playing in the castle, although they've had to help repair it a few times. We have kept adding to the props as children come up with new ideas and interests. The boys are often difficult to engage in creativity, but they all queued up to make helmets and crowns to wear in the castle. They also enjoy pretend sword and shield fights.

Staff and children bounce ideas off each other of what else to do. Vines hanging down the walls are made of tissue paper, and parents helped to make the roses to go on the walls. Children have also stuck pictures of food on to paper plates for the banquet table, where they hold elaborate meals.

We even held a ball in the castle, since named Red Heart Castle, to raise money for the British Heart Foundation, because one of the children who attends nursery has a sister with a hole in her heart.

The children have lovely role-playing sessions in the castle. There is space for them to act out their imaginations in an area where they do not feel watched, especially if they hide in the dungeon. Children love climbing up to the ramparts to look out over the nursery. It's a social area where they go with their friends, or by themselves just to contemplate.

The surprise appearance of a firebreathing dragon overnight really excited the children. We discussed why he may be at  the castle and what we could do to scare him away. This led the children to make magic spells. It has really helped their storytelling and narration skills.

Some of the children read about animated trees with big faces and loved the magic element of this. It inspired us to put up trees around the castle to create our own enchanted forest. Children now enjoy going there to hide and read books behind the trees.

The parents also think the castle is fantastic and can't wait to see what the staff and children have added next.

Sally Squires spoke to Annette Rawstrone.