This is one I watched in grade school school in the 1970s/early 80s.
It was a film (of the projector variety), color, and it may have been dubbed into English from another language. My gut tells me that the people in the film weren’t American, but that’s quite possibly a faulty memory.
The only scene I really remember is two of the children pretending to be American Indians tying up a third, younger child to a post near the water’s edge. They soon forget about him, and the tide starts to come in. Mom saves him not really in the nick of time, but he’s definitely getting wet.