Explain the relationship between observations and hypotheses

1. They are (impossible for both to exist together at the same time). 
2. (more than two, but not a lot of) explanations (of why things work or happen the way they do)make up an (instance of watching, noticing, or making a statement). 
3. (more than two, but not a lot of) (instances of watching, noticing, or making statements) makeup an explanation (of why something works or happens the way it does). 
4. There is a back and forth/equal between people and energetic/changing interaction between them.

The answer would be sand and gravel