"Crouch down and touch the floor," instructs Charlie Lewis, senior education officer for the environmental charity Environ. "What do you think it's made of?" The nine children crowded into the foyer of Environ's EcoHouse shout out their guesses of "cotton" and "wood" but Charlie shakes her head.
In fact the stripy, durable mat is made from old aircraft tyres. Like everything in this two-storey red-brick building, it has been made with the planet's future in mind.
The house was built as a gatehouse for Western Park, Leicester, but when Environ leased it in 1989 it was turned into a showcase for renewable building materials and technologies. It aims to demonstrate that anyone can do their bit for the environment, even a group of eight and nine-year-olds from nearby Marriott Primary School.
"As we're going round, I want you to think of one thing that you could each do when you go home to help make a difference," says Charlie. First stop on the tour is the kitchen, where Charlie points out the worktops made from recycled coffee cups, the splash-back made from melted-down yoghurt pots, and wooden window frames.
"White plastic window frames are one of the worst things we can do for the environment," she explains. "These ones are wood but they come from a forest where a new tree is planted every time one is cut down. And the floor is made from cork, which is made from tree bark, so trees needn't be cut down at all."
We feel the insulating properties of the flooring when we head upstairs into the living area. Rather than letting heat sink through the floor, the cork reflects it back and as the warm air rises it helps heat the upstairs rooms. In the lounge, Charlie invites the children to feel the temperature of different materials placed on top of a hot radiator. They soon find that single glazing lets a lot of heat through, while heraflax, a natural material made from flax fibres, stops the warmth from escaping and is therefore a better insulator.
There are more exhibits on saving energy and producing it sustainably in the roof room. In one corner, a giant lightswitch enables the children to choose between illuminating an ordinary light bulb or an energy-saving one.
When one eager young boy switches from the former to the latter, a meter showing the amount of energy being consumed slows considerably. "The low-energy bulb lasts 10 times longer than the normal one and uses less energy," says Charlie.
With the indoor tour complete, we head outside to the EcoHouse garden.
After visiting the butterfly patch and snaking our way along a shady path lined with slug-laden composting bins, we gather around a clear, deep pond.
Frogs croak from submerged hidey-holes and midges dart about, as Charlie explains that the lush green reeds we see are helping to clean the water.
"All the water in this pond used to be dirty water," she explains. "But the reeds naturally filter out the impurities."
We learn more about why we should use water wisely in a classroom exercise following the tour. Charlie uses a beaker of liquid to demonstrate that the world's water is a finite resource, much of which is locked up in the ice caps. She then asks the class to complete a giant jigsaw showing how water makes the journey from rainfall to our taps.
After the class, I ask nine-year-old Holly Thompson if she's thought about the one thing she plans to do when she goes home to help reduce her impact on the environment. "I think I'm going to turn the tap off when I clean my teeth to save water," she says thoughtfully.