Ukrainian children streamed into new schools across central Europe for the first time on Thursday, staying abroad after others returned home to familiar classrooms and the dangers of war.

With many having not attended previously as their parents, after fleeing to central Europe, kept them out of local schools in hopes of a quick end to the war, the continuing conflict had school systems in Poland, Czech Republic and elsewhere braced for potentially hundreds of thousands of new foreign students.

At Warsaw's Tadeusz Gajcy School No. 58 where refugee students, some wearing traditional vyshyvanka embroidered shirts, walked to class with their backpacks in tow, Ukrainian flags stood inside the entrance.

For Jaryna Jasny, 42, the safety of the environment there outweighed any desire to return to her village near Kyiv, where she worried about the dangers her 12-year-old daughter Melania might face on the daily trip to and from school.

"The next serious discussion about going home will be in November," she said. "Because now the situation in Ukraine simply does not allow it. We have to wait a little longer."

More than 7 million Ukrainians have fled abroad since Russia invaded in February, nearly 4 million seeking refuge elsewhere in Europe, according to United Nations refugee agency data.

Poland is hosting nearly 1.3 million, more than any other country.

ALARM BELLS NOT FOR A BOMBING RAID

Tadeusz Gajcy School's principal Wieslawa Dziklinska said that, with the new intake, Ukrainian children now make up nearly half her school's headcount, and integrating them was challenging.

Many of those who enrolled the previous term did not want to participate in Polish language classes because they hoped to return home quickly while alarm bells during evacuation drills brought back memories of war, Dziklinska said.

"The prolonged conflict means that these children have no sense of security," she said outside the school.

"It took us three weeks to teach the children little by little how to evacuate because they had to adjust to leaving the building safely and we had to get them used to the idea that it was not a bombing raid."

Also preparing for the task of integrating many more Ukrainian students were school authorities in Czech Republic, which is hosting around 400,000 Ukrainian refugees - the largest per-capita number in Europe according to the UN data.

"We have a problem with the high schoolers because they have an 11-year system in Ukraine," Czech Education Minister Vladimir Balas told reporters. The Czech system takes 12 years to finish.

Educators there and in Poland have said they will have a clearer picture of overall numbers of Ukrainian students after Sept 1, once the new term is in full swing.

Some haven't stayed.

Alla Andrushchenko said her eight-year-old was able to absorb information in Polish easily but her 15-year old had difficulties learning in a foreign language. This convinced her she needed to return to Kyiv despite the war.

"As they say, nothing is better than home," Andrushchenko said.