Why do children go to grandma's house for the summer?

Belong to the category of traditional customs. Young people nowadays don't know much.

I asked my grandmother, and she said it was because the long summer in the countryside was very busy and the weather was getting hotter and hotter. The children will go to her grandmother's house for the summer vacation, and it also means to lighten the burden on the busy young couple (no need to take care of the children).