Here are the corrected sentences:

1. Our teacher said that the World Wide Web **was** a free space for people to share knowledge.
2. The scientist explained that they will conduct more tests **to ensure** the consistency.
3. My brother **told** me that the new computer chip was much more efficient than the previous one.
4. The chemical instructor explained the experiment in such a way that **it was easily understood**.
5. Our body uses calcium to build **healthy** bones and teeth, and keep **them** strong as we age.
6. They would have a good chance of survival if they can get proper medical care in time.
7. The man took off his shoes **so that he didn’t** make a noise when he entered the room.
8. Drinking enough water is a vital part **because** it keeps your body functioning **properly**.