A woman stands at the side of the road, looking mournfully at a flat tyre. Do you pull over and help her change it? If it was a man, would you do the same?
If you answered yes to the first question but no to the second, you are reinforcing a "damsel in distress" syndrome that could have grave consequences for our economy.
It is a term used by engineering apprentice Jessica Taylor. As the only female technician out of 180 at her company, Taylor has got used to men offering to carry heavy parts. Back at school, every time she used a drill in woodwork class, she would be waiting for the usual "won't you let one of the boys do that?" comments.
Taylor has always loved taking things apart and seeing how they work. At primary school this did not make her stand out particularly, but by secondary school it did. That is where she started being "the only girl". Now she is the one woman of 40 students in her mechatronic engineering class at college, which is part of her apprenticeship at Avery Weigh-Tronix, a maker of industrial weighing machines.
How young women like Taylor end up in the minority, and what happens to turn teenage girls off physics and, more widely, engineering is a question that has drawn plenty of research and just as many campaigns. One of these, Wise, was launched as Women Into Engineering and Science 30 years ago. The Women's Engineering Society emerged even earlier, in 1919, when women who had worked in engineering roles in the first world war lobbied to keep them when the war ended.
Now this question must be top among the priorities of new education secretary Nicky Morgan, because for all the initiatives so far, the figures remain dismal.
For more than 25 years, only a fifth of students taking physics to A-level have been girls, despite equal success between the sexes in GCSE physics and science, according to the Institute of Physics.
That pattern of dwindling numbers continues as girls move into the workplace. Women made up just 4% of apprenticeship starts in engineering but more than 90% for hairdressing in 2011-12, according to unionlearn, the TUC's skills organisation. The UK has the lowest proportion of female engineers in the European Union, at less than 10%.
There are too few women engineers in the UK – and there are too few engineers altogether. George Osborne will struggle to lead an effective "march of the makers" if the sector fails to draw on the whole working population.
So the workforce misses out due to stereotyping and women themselves miss out, too. Engineering has long paid higher-than-average salaries, and pay in the sector is on the rise. The average advertised salary for engineering jobs is up 5% over the past year to £36,391, according to jobs search engine Adzuna.
If doors to the rising number of engineering jobs are to be opened to more girls, action is needed from four sides: business, the current workforce of female engineers, parents, and the education system.
The business case is clear. Beyond the urgent need for a wider recruitment pool, businesses know that better diversity has a direct impact on their bottom line. And yet the Institution of Engineering and Technology found in its latest annual survey of skills that more than a third of employers were not taking action to attract women into the sector.
That goes some way to explaining why half of the women who study engineering do not go on to jobs in the field, according to manufacturers' organisation EEF. It wants the industry to work harder to quash the idea that an engineer "is the man who comes to fix the photocopier", in the words of EEF policy adviser Verity O'Keefe.
There are some promising examples. When consultancy Accenture was unable to meet its target of 50% female IT apprentices at its Newcastle office, it helped set up after-school coding clubs for girls. The company also runs app building workshops for girls under the Stemettes initiative.
Other projects have seen women going into schools to talk about their careers, including under a recent national campaign called Your Life.
For women who have become part of the minority in engineering, there is also a growing recognition of the need for mutual support. Keeping female engineers in the sector is still a problem, says Adeline Ginn, who founded Women in Rail after she noticed how many women in her industry were talking about a career change. She now runs self-confidence workshops and networking events for women.
But for all the work by businesses and charities, too often girls' horizons are narrowed early on. Parents and schools are key to changing this. Apprentices like Taylor are the ones who resisted the "that's not for you" attitude of so many adults around them. But it should not be just the defiant girls who make it.
Both young girls and boys will be making sandcastles on sweltering beaches this weekend. Parents and schools need to ask how they can keep them all interested in designing, building and fixing. Our neighbouring countries, where engineering is held in higher esteem, are way ahead on this.
All of us in the UK would do well to adopt the mantra of the Women's Engineering Society: "Girls can't what?"