About 300 schoolchildren who tried to march to Parliament from the ANC's "people's assembly" on Thursday were pushed back to the Grand Parade by police.
Some wore T-shirts with the words "Hands off our Liberator" alongside a picture of President Jacob Zuma printed on it.
The schoolchildren sang shrilly as they moved up Parliament Street.
"We want to see President Jacob Zuma making his speech," said a Grade 11 pupil from Philippi.
There with the blessing of her parents, she said she wanted Zuma to know that school was not free, like he said.
"We have to pay a 'contribution fee', buy Typek paper, and books. It is not free."
As they headed toward Adderley Street, they were stopped because they did not have a permit to march. Favoured as a protest march route, Adderley was off-limits because EFF supporters were already there.
Shouting the slogan of their political forebears "each one teach one" the children pushed against the riot police, who leaned into their small bodies with their shields.
Some water was sprayed and a stray stone flew into the air. The children moved back, shouting "Zuma! Zuma! Zuma!".
Congress of SA Students' leaders were in front of the march, which was eventually turned back to the Grand Parade.
ANC supporters were asked to join the party at its own State of the Nation celebration at Grand Parade, near the bus station. The party is pulling out all the stops to reconnect with its constituencies after its poor performance in last year's local government elections.
The Grand Parade celebration was a mixture of hard dance music, gospel favourites, and smooth jazz.
Zuma is expected to join in after his address, which is scheduled to start at 19:00.