Spanish parents are revolting – against homework. The CEAPA (which represents 12,000 parent/teacher organisations) is organising protests against what it claims is too much homework set by schools. A recent survey revealed that 82% of parents asked believed it was too much or excessive. Over half thought it harmed family life. And with a few caveats, I couldn’t agree more with their complaint.

Interestingly, compared with other countries, the estudiantes have it relatively easy. In 2014, the OECD recorded average weekly homework assigned to 15-year-old students across various countries, and it turns out Spanish students don’t know how lucky they are, with a mere 6.5 hours. Finnish pupils dodge the bullet with a skinny 2.8 hours. Shanghai clobbers its students with 13.8 hours (so they know what it feels like to be a teacher, I imagine). The UK doles out a comparatively palatable 4.9 hours. Given that Programme for International Student Assessment chart-toppers Finland and Shanghai appear at either end of this survey, there doesn’t appear to be a clear link between length of homework set and systemic grade outcomes.

So what does the research say about it? A 2001 meta-study by the National Foundation for Educational Research concluded that there was “a positive relationship between time spent and outcomes at secondary level” but “evidence at primary level is inconsistent”. And even at secondary, homework “explains only a small amount of variance in pupils’ achievement”. More recently John Hattie’s seminal Visible Learning study concluded that homework overall had an effect size of 0.29 – in other words, a very small impact. He too noted a difference between the effect on young pupils (0.15, minuscule) and older children (0.64, significant). Other studies concur. So if there is at least some utility, are the Spanish parents right to rebel?

Si. Because there is a huge variance between the effect different types of homework have on students. And homework differs from classwork in many ways. It’s normally done independently of supervision; it requires that the task is understood, and that all resources to complete the task (from IT to prior, understood knowledge) are availableThe student needs uninterrupted time and space to finish it, and the qualities of character to complete it. Obviously, mileage varies enormously in all of these categories. In a classroom you can attempt to create a controlled environment where conditions are optimised for everyone’s benefit. But setting homework is an act of faith about what will return; a boomerang thrown into the darkness.

Homework by candlelight in San Cristobal, Venezuela. Photograph: Carlos Eduardo Ramirez/Reuters

Plus, some homework is useful, and some is not. One thing that amazed me when I entered teaching was how much homework appeared to be entirely mad, and set for little purpose beyond bureaucracy. Writing a poem about how you felt about litter was one of my favourites, but there were countless other examples. Writing a letter from Jesus about what it was like to be on the cross. Making “wanted” posters for Mr Hyde for English teachers. Colouring in the Great Fire of London for history. Writing scripts for roleplays about Greek medicine. Building volcanoes out of papier mache for geography. I mean, come on. These kind of activities indicate a purposelessness that we need to say goodbye to for ever in teaching. Set meaningful homework, or not at all. It’s their time you’re wasting.

For example, asking pupils to read independently is great, and useful at most ages, although by itself it won’t help someone struggling with the basics. It demonstrates what is called the Matthew effect: to those that already have, shall be given. In other words it’s the children with poor background knowledge or difficult home environments who benefit least from it, and the most fortunate who get any effect at all. Which isn’t an argument against homework, but a reminder that when you set it, you have to be aware of the different impacts it can have.

Of course the teacher’s lens is important here too: homework produces marking. And if you set it, the student deserves constructive feedback. But if you see 200+ children as a secondary humanities teacher every week, weekly marking becomes a Sisyphean task. Even flicking and ticking the toils of that number of pupils becomes an extra day out of your week. And the effect of such minimal feedback is microscopic at best. Given that this might burn anything up to 25% of your notional working life, it’s heart-breaking, not to mention pointless.

Finally, the parents’ view: homework steals family time that doesn’t get refunded elsewhere in the week. And that is indisputably true, and the theft is compounded when the return is so small in general. Those few hours between getting home and closing your eyes are precious to the inter-family relationship. If you’re going to steal any of that, you better be damn sure that the reward is greater than the loss. And for a lot of homework, for a lot of children, it just doesn’t add up. Abajo el sistema opresor – down with the oppressor – as they say in Spain.