During World War II, sometimes there were very bad things happening in some parts of Germany, like bombs falling down from planes and making big holes in the ground. People didn't want children to get hurt, so they had to be very brave and leave their homes and families to go to a different place that was safer.
This was called an evacuation. Evacuations happened when lots of children would get on trains or buses with their teachers and other grown-ups who could take care of them. They would leave the cities and go to the countryside or small towns where there were no bombs falling down from the sky.
When they got to their new homes, the children would either stay with people who lived there or stay in special buildings that were made just for them. Sometimes they would be in very big groups with lots of other children they didn't know, but they still had nice people to take care of them and make sure they were safe.
It was hard for the children to leave their families and homes behind, but it was important to keep them safe from the bad things happening in the cities. After the war was over, the children would go back to their families and homes and could rebuild their lives.