“Stop,” yells the small group of five-year-olds, sitting with their teacher on the carpet of a Leeds primary school classroom where they are learning about the dangers of tablets and syringes found on the streets and in the playground.

“What do you do when you find a tablet in the street?” their reception class teacher Amanda Johnson asks once more, holding up a bottle of pills.

The children stretch out their hands and shout “Stop” and the bottle is placed on a piece of red card, which represents a red traffic light.

“Why do you stop?” she asks. “You could die if you take them,” answers one boy. Miss Johnson warns that they could be dangerous for children. “And what else do you do?” Another boy suggests: “Leave them.”

But Miss Johnson urges them to tell an adult. “Don’t leave them for another child to find.”

Solly Coles, five, says the weekly lessons make him more careful when he plays out in the streets. “There’s a lot of mess in my street. If I see something like glass or a tablet I tell someone.”

Nadia Begum, four, says she tells her baby sister t be careful. “That’s a good idea, to tell your brothers and sisters to be careful if they find something in the street,” adds Miss Johnson.

She recalled the time a syringe was found in their playground at Bankside primary school in Harehills. “What did we do? We left it alone, we told a teacher, we put on big gloves and took it away and put it safely in the bin.”

The warning lessons apply to anything found in the street that could be harmful, from half-drunk bottles of milk to tablets and needles.

The early-years lessons are recommended in the updated guidelines on drugs education in the city, which covers illegal substances, prescription medicines, alcohol and cigarettes.

Drugs education adviser Penny Vine said drugs had become a normal aspect of every child’s life. “Anecdotal evidence from teachers of very young children shows they are aware of legal and illegal drugs.

“Some teachers in Leeds have reported they feel that their children know more about drugs than they do. Though this might appear to be the case because of the language children use, research tells us they still lack the skills, knowledge and values necessary to make safe choices.”