Describe this painting as fully as possible.

This painting, called "The Sunday School Walk" by Albert Anker, shows a group of children and what appears to be their teacher or a grown-up leader on a walk. There are many children of different ages, some boys and some girls. They are dressed in old-fashioned clothes, probably from the time the painting was made. Their clothes have simple designs and colors like browns, whites, blues, and reds. The children are gathered together, mostly in the center of the painting. Some of them are looking around, some are talking to each other. One child on the far left, dressed in dark clothes, is crouching down and holding something red. Another child, a boy, is walking a little ahead of the main group near the center. The grown-up, dressed in dark clothing, is standing tall in the middle of the group, seemingly leading them or looking after them. In the background, there's a hilly landscape with green fields and some trees. On the right side, you can see a house with a red roof, which looks like a farm or village building, suggesting they are in a rural area. The sky is bright blue with a few clouds, indicating good weather for a walk.