For four days, a group of students at St Joseph's School in Wadala pored through garbage, sifting, separating and weighing it.
The exercise was part of a waste audit students were conducting with GreenLine, an environment forum of the Don Bosco Development Society, which works with various schools on environment-friendly projects.
The students found that their school was generating an average 200 kg of garbage every month. It was time to take stock.
"It was only after doing this that we realised how much waste we generate and how we can be more careful," said Rhishabh Deshpande, a student who was involved in the auditing process.
Greenline works with 30 schools across the city on a variety of campaigns.
"Students are becoming conscious of the different types and quantities of waste. Earlier we would find their knowledge was based on guesswork," said Savio Silveira, director of Greenline.
"With growing consciousness they are also realising that their responsibility does not end by just putting the waste in the bin."
Students of St Joseph's are now working on coming up with a waste policy at their school where they will continue to segregate the garbage, recycle that which can be recycled and compost the food waste. Earlier it was all just dumped together and hauled away by the municipal corporation.
"Our target is to bring down the waste generated to zero," said Padmini Dev, a teacher at St Joseph's who guides the Eco Club.
A slew of other schools - including Auxilium High School at Wadala, St Paul's High School at Dadar and Duruelo High School at Bandra - are also in the process of conducting their audits or writing up their findings.
At Don Bosco School in Naigon, where students completed their audit this week, some said they faced jibes for their unusual interest in garbage, but soldiered through all the same.
"People called me a kachrawali, but it doesn't matter what people say, I had fun doing this," said Beverly D'Souza, a Class 8 student of Don Bosco.
"I've always been interested in the environment."