A group of schoolchildren intently eye up a row of chocolate bars temptingly laid out before them, but all is not as it seems.
Rather than picking out their next calorie-laden snack, these pupils at Wybourn Community Primary School are trying to arrange the treats in order of how much sugar they contain.
They are at the forefront of an innovative project in Sheffield to curb the rapid increase in child obesity, which is a nationwide problem.
READ MORE: Child obesity hits highest ever level in Sheffield
The Sheffield-based charity SHINE Health Academy is working with schools including Wybourn to educate youngsters from an early age about healthy eating and exercise, and to track more precisely when and why primary school children start piling on the pounds.
National figures published by NHS Digital show 22.6 per cent of children are overweight or obese when they join primary school, but that percentage leaps to 34.2 by the time they leave.
In Sheffield, the leap is even more pronounced, going from 22.3 per cent to 35.6 per cent over the seven years between reception and year 6.
READ MORE: Tributes paid to much-loved former Sheffield councillor
At Wybourn, children who joined reception in 2016 are now being measured annually in an attempt to identify patterns which could help prevent weight gain.
The school has also received training from SHINE to help deliver advice on healthy lifestyle choices to children and parents in what the charity's founder Kath Sharman describes as a 'non-threatening and non-judgemental way'.
"This is an amazing opportunity to work with such enthusiastic staff who are really keen to promote the health and wellbeing of the children they teach in all aspects of achieving a healthy lifestyle - not just around weight," said Ms Sharman.
READ MORE: Building work starts on £2.1m extension at Sheffield primary school
"Schools are in prime positions to really make a difference but they often greatly underestimate the impact they can have in tackling problems."
Wybourn already ran a free breakfast club for pupils but has introduced healthier options as part of the collaboration and given parents menus with healthy lunchbox ideas.
Older children regularly run Tyler's Mile, named in memory of a late pupil, while younger ones do at least one session of 'high-impact activity' in the classroom each day.
READ MORE: Community rallies to support Sheffield businesses ravaged by fire
The school even incorporates exercise into more academic subjects through activities like 'Maths of the Day' in which children must get on their feet to solve problems.
There are 'Stay and Play' sessions where children work out with their parents, and a boot camp for teachers which not only helps them stay in shape but reinforces the message to pupils that exercise is for everyone.
Perhaps the most successful innovation, however, is the SHINE after-school club, an optional 10-week course for year five pupils which has proved so popular since being introduced a year ago that there is always a waiting list.
Participants take part in group exercises and learn all about healthy eating through hands-on activities from analysing the ingredients in soft drinks and sweets to making fruit kebabs and smoothies.
They are weighed at the beginning and end of the course, enabling the school to provide more tailored support. The latest group, for example, has more more underweight members than overweight ones, so sessions focus on what they can do to achieve a healthier weight.
It is too early for any meaningful statistics showing the impact, but deputy headteacher Gillian Booth believes the new approach is already making families think and talk more about their health.
"Conversations about health, keeping fit, being active, drinking enough water, being outdoors etc are commonplace," she said.
"There is a definite understanding from a high percentage of children, especially higher up the school, that looking after yourself and your body is important.
"This week during an assembly I joked about wanting to share sweets, and a girl pointed to me and said 'but Miss, you're too healthy to eat sweets'.
Emmanuel Junior Academy, in Waterthorpe, has also teamed up with SHINE.
When pupils there were measured, 31 per cent were found to be overweight or obese but 11 per cent were deemed underweight.
Emmanuel already held the Healthy School Award but has stepped up the amount of time children spend exercising, training sports leaders in year five to organise activities, and runs food and cooking sessions.
The after-school sessions with SHINE have focused on giving children all the information they need to make healthy choices, as well as promoting confidence, self-esteem and emotional wellbeing. An awards session at the end of the 12-week programme enables parents to celebrate their children's success.
Headteacher Charlotte Newton-Wall said the change in those taking part in the 'fantastic' scheme was unmistakable.
"Their lunchboxes are healthier and the conversations they are having about choices are more educated," she said.
"They are also spreading the ‘healthy lifestyle’ word… other children are requesting to take part in the programme and that is why we decided to train staff within our setting.
"As a result, some pupils' weight and waist circumference has decreased, in some cases significantly."
Ms Newton Wall believes primary schools are well-placed to help families prevent children developing long-term health risks, but believes more must also be done at secondary schools to prevent this work being 'undone' when children have more freedom to indulge in sugary snacks.
Both Wybourn and Emmanuel are seeking to educate the whole school about healthy living - not just those with weight problems.
And they are taking a holistic approach, incorporating the measures into everyday life at the school and recognising the importance of emotional wellbeing, which is at the root of many eating problems.
The aim is to prevent children forming unhealthy habits which could affect their long-term wellbeing, making healthy lifestyle decisions second nature to children and their parents, and to intervene early if problems do develop.
"Our families are beginning to embrace the link between health and wellbeing, and to accept that we mean the best for their children in every way – academically, emotionally and physically!" said Ms Booth.
"I would definitely recommend that schools look closely at the needs of their children and families, and seek out other establishments or experts to help them move forward with turning the tide of obesity - before it's too late!"
'It's potentially life-saving education'
Amir Naseem, aged nine, took part in the SHINE after-school club at Wybourn and enjoyed it so much he joined the charity's out-of-school programme.
His mum Emily Collins says the difference since he started last autumn has been amazing.
"He's eating so much more healthily, the weight's dropping off him, he seems much more chilled out and he even sleeps better," she said.
"We live across the road from a pound shop and unbeknownst to us he had been going there frequently and buying two Mountain Dew drinks for a pound.
"Amir's never been particularly fat and he's always been active, doing parkour and swimming a lot, but he had got a bit chunky.
"The course was all about awareness and food choices. If you realise you have to burn so many calories to eat a chocolate bar the penny drops and you start thinking 'do I need that bar of chocolate?'
"Amir's stopped drinking Mountain Dew and switched to zero-sugar drinks, and he's swapped crisps for olives and seafood sticks
"He's done it himself. I just have to stand by him and help him make those changes.
"He did have a bit of a weight problem but I thought it was just puppy fat and it would drop off.
"It's easy to be kind of deluded about it but when you hear what the consequences could be, like fat building up around the organs, high blood pressure and diabetes, it really makes you think.
"It's great how they explain everything like portion sizes and the different food groups. It's potentially life-saving education.
"I think this should happen at other schools. When you walk around Sheffield and look at the size of many children you realise there is a problem.
"The better you eat, the better you feel. If you're just eating junk food, that does take its toll.
"As a parent you have to take some responsibility for the size of your child but it's helpful to have support from their school and organisations like SHINE, who have been fantastic."
* SHINE is campaigning for more funding to help severely obese children. You can sign its petition at https://petition.parliament.uk/petitions/205447.
* For more about SHINE and the work it does, visit www.shinehealthacademy.org.uk.