Opponents say this will reduce the post-lunch period to mere child-minding.
One in five Italian primary school children attends tempo pieno (full-time school), which was introduced in the early 1970s to help families where both parents work. In big towns, where there are more working mothers, the figure rises to more than 30 per cent.
Tempo pieno children go to school from 8.30-4.30pm, Mondays to Fridays, clocking up an impressive 40-hour week, while the remaining 80 per cent of primary pupils do five hours each morning, from Monday to Saturday, and come home for lunch.
Many state schools offer both options. Lessons are organised differently, with two teachers allocated to each tempo pieno class, while tempo normale classes are taught by a range of subject specialists working in teams.
Critics of tempo pieno say that since pupils cover the same syllabus whichever option parents choose, lessons get diluted. Children come home tired, with little time left for after-school activities.
In the proposed reform, all pupils will have 27 curricular hours. Schools must also offer three optional hours, the content of which they will be free to choose. For those children in tempo pieno classes, the minister has added on another 10 hours, to reach a total of 40, which are simply allocated to meal times.
Supporters of tempo pieno see this as the beginning of the end of a valid educational alternative. For the Mayor of Rome, Walter Veltroni, a possible centre-left candidate to face Silvio Berlusconi in the next general elections, tempo pieno is a "way of life which was achieved only through hard work".
The Saturday protest was one of the more unusual Rome has seen in recent years. Orchestras, clowns, pets, balloons and lots of Nutella sandwiches kept children happy as they marched through the streets for three hours, while political slogans took second place to an exuberant stream of nursery rhymes.