homework strike this month in protest against the unacceptable amount of after-school tasks their children are given.
The homework load of Spanish children has long been a sore point with some parents, who argue that the burden is too great, places too much pressure on pupils and eats into family time.
According to a 2012 study by the Organisation for Economic Co-operation and Development, Spanish 15-year-olds have 6.5 hours of homework a week compared with an average of 4.9 across the 38 OECD countries.
The Spanish Confederation of Associations of Mothers and Fathers of Students (Ceapa) has decided that enough is enough and is calling on parents whose children attend Spanish state schools to boycott weekend homework in November.
"We've lost a bit of common sense in this country when it comes to talking about education and we've got a system in which boys and girls free time has disappeared", said Jos Luis Pazos, president of Ceapa.
"Schools are passing on tasks to families that they shouldn't be."
"It starts with children from the ages of three to six doing half an hour's homework every day."
"For us, that's an unacceptable situation". Pazos said Ceapa disagreed profoundly with the notion that children should endure huge amounts of homework in the hope that it would ensure them a better future.
"They should be happy when they're little and learn that life isn't just about someone telling you that you have to suffer inexplicably", he said, adding:
"The model needs to change because society has changed." Schoolchildren have to fit their homework around the school day, which varies from region to region and school to school, but starts early from around 8am or 9am and finishes anywhere between 2pm and 5pm (with a long lunch break).
However, schools are increasingly using an 8am-2pm timetable to save money and in the face of evidence that suggests the longer hours do not yield better results.
Ceapa, which represents 12,000 parents associations, said the strike had received support from both parents and some teachers.
Parents waiting to pick up their children from the Padre Coloma infant and primary school in eastern Madrid on Wednesday afternoon said finding the right balance between homework and family life was sometimes tricky.
Patricia Ruiz said her eight-year-old son would be getting five tasks this weekend, which would take him about an hour and a half - long enough to cause arguments.
"I spend the whole day trying to get him to do his homework otherwise he'll be punished", she said.
Ricky Prez, a security worker, said he thought the school was giving pupils about the right amount:
"It's a normal level of homework here; they're not doing it all day". Beatriz Velsquez, who works in cleaning, reckoned children now ought to be counting their blessings.
"When I went to school, we had homework all week and at weekends about 14 hours a week [in total]", she said.
"My children have it easier as they don't have as much as I did, or as much as they do at other schools."
"They have time to play, which is the most important thing."
"They need to study, but they also need to have the time to be kids".A spokesman for the education department of Madrid said homework was a matter for individual schools rather than regional governments.
"They're the ones who know best what the need is in each case", he said.
"It's a question of autonomy: the teachers know what the needs of every student and every class are.