This^^ Every kid reacts difference, but allowing them to finish their sentence on their own helps them learn that people have the ability to be patient and wait for them to get it out. Speech therapy is a great recommendation, though I would search for professional sources outside of just school. My therapy as a kid helped a bit, but those lessons never stuck because the sessions were grouped and little ADHD me wasn’t able to keep focus long enough to keep the tips in my head.