my brother is the third grade has a science test tomorow but didnt bring the book with him!!!! he has a study guide though. and there were 3 pages loong he did all of them except for these questions can u help us out?
1) In 3-5 sentences, explain how messages travel in our bodies.
(this was a lesson about the nervous system)
2)In 3-5 sentences, explain how the breathing model works. (respiratory system)
3)In 3-5 sentences, explain how the model arm works. (muscle system)
4) In 3-5 sentences, explain how the pumping blood works at rest and in periods of activity. (i think they mean the pulse of the heart this is about the circulatory system)