Our intervention design process was firmly rooted in the communities we aimed to serve. We ran workshops with Welsh head teachers and council catering leaders to better understand the constraints they face, how circumstances vary between different schools and councils, and where leverage points for intervention might be. We visited primary schools in Torfaen, Cardiff and Caerphilly to observe on-the-ground school meal delivery and talk to chefs, teachers, lunchtime supervisors, pupils of various ages and their parents.

We also researched how school meal uptake has been improved in the UK and internationally. This included examining academic literature, interviewing school food professionals and talking to headteachers in schools with almost 100% school meal uptake. We also considered the behavioural science around how parents and children make choices relevant to school food.

We used a design-led approach to inform this research, iterating and testing several intervention prototypes with pupils and parents in multiple primary schools.

Leveraging the default bias to smooth the path to ordering school meals

In response to parental and pupil feedback on prototype ideas we developed, SMCMIM emerged as the most likely to be cost-effective, feasible and scalable. This intervention operates on a straightforward premise: setting a whole school expectation that pupils will partake in school meals for a designated month unless their parents actively choose to opt out through direct contact with the council catering team.

SMCMIM tapped into the well-known default bias – our tendency to stick with the default or pre-set option (think of that unchanged ringtone on a new mobile phone). We theorised that by flipping the default option – shifting from an assumption that pupils will bring a packed lunch unless their parent actively selects a school meal, to pupils receiving a school meal unless parents specify otherwise – we could nudge more students to try out school meals.

Fostering a shift in social norms

Social norms are the implicit rules that define what behaviour is acceptable or expected within a group or community. They explain why people form orderly queues in the UK, but adopt what can appear to some as a more haphazard approach elsewhere. SMCMIM aimed to capitalise on the influence of social norms by advocating for default participation in school meals. The goal was to foster a critical mass of children joining in and catalyse a shift in whole school behaviour. Ultimately, the aim was to make eating school meals the norm and bringing packed lunches the exception rather than the rule.

The long-term aim was to prompt lasting improvements in school meal uptake by allowing pupils who typically opt for packed lunches to get better acquainted with, and hopefully develop a sustained liking for the food on offer at school. While we piloted making school meals the default option for one month only, we were also interested in exploring the feasibility and desirability of its permanent implementation as part of this trial.