Around 15,000 school pupils gathered to protest over a government plan that they say has failed to improve education in Amsterdam today.
Travelling to Museum Square from around the country, some lit fireworks and threw smoke bombs, and 20 were arrested for disorderly conduct, police said.
But there was no repeat of clashes with riot police that took place at the same spot on Monday.
Police, who estimated the turnout at around 15,000, said the arrests were for "disorderly conduct, vandalism, throwing eggs, rowdiness, that kind of thing," said a spokeswoman.
The students, organised by a National Action Committee for Students, oppose a law brought in last year stipulating that students receive 1,040 hours of lessons per year.