PORTO ALEGRE, Brazil (Reuters) - Tens of thousands of students in southern Brazil have been gone a month without seeing their classrooms after catastrophic floods submerged some schools and turned others into shelters, raising concerns about their mental health.

Of Rio Grande do Sul state's more than 2,000 public schools, nearly a fifth remain closed, affecting some 185,000 students.

"We have children who are completely traumatized. When it starts raining they panic," said Rio Grande do Sul state Education Secretary Raquel Teixeira.

Rains that started in late April have swollen several rivers and lakes in Brazil's southernmost state of Rio Grande do Sul to record highs, causing floods that killed at least 169 people and left more than 580,000 displaced, according to state officials.

In the northern part of state capital Porto Alegre, near the Guaiba river, which still is above flood levels, primary school Brasilia remains partially under water. The school's soccer court is a pool, while classrooms and books are covered in mud.

"We have impacts on infrastructure, physical and material; we have pedagogical impacts; we have psychological, and we have emotional impacts", Teixeira said.

Elsewhere in Porto Alegre, at Roosevelt school, principal Marcio Freitas said employees know they will be the emotional support for parents and about 800 students as soon as they get back for classes, which are expect to resume by early June.

"To have this situation (of flooding) in our last year of school, plus to have lost our last years of elementary school (to COVID-19), gives us ... a very bad feeling," said Sophia Souza Assumpcao, a high school senior at Roosevelt.

Freitas, the principal, said he has faced many challenges working in public education over the year, but none as big as this one. Still, he said education gives no time to suffer.

"If you fall you have to get up quickly. That's life in education."

(Reporting by Diego Vara; Writing by Andre Romani; Editing by Aurora Ellis)

By Diego Vara