1. I would not even mention to fourth graders that this is a fragment unless we were syntactically analyzing the passage. Even then, I would not make a big deal about it.

2. This sentence is a good example of the purpose of "correct" punctuation. In processing this sentence the reader gets "she's a housewife while I am in school" which suggests that when the writer is not in school, the mother is not a housewife. Then the reader gets the "my mom goes out" which changes the meaning of the "while" clause, thereby confusing the reader. 
     Although some primary school teachers think that fourth graders can analyze clauses and understand the grammatical explanation, I seriously doubt it -- some of my college Freshmen have trouble with it. In working with fourth graders, I would simply appeal to their sense of a sentence -- Does it mean "She's a housewife while I am in school" or does it mean "While I am in school, my mom goes out"? In other words, I would not use the word "clause."

3. This "when" clause could also be interpreted as modifying "thinks," the verb in the main clause.

4. Note how, in analyzing their own writing, students will run actoss fragments such as this -- without a subject of verb. Because the majority of the sentences they have analyzed have subjects and verbs, and becaue we teachers tell students that they should have, students will see for themselves that something is wrong. Teachers should simply suggest that the fragment can probably be joined either to the preceding or the following sentence. In this case, "a one story *with* five rooms, plus a pantry."

5. In discussing "had" in Level Two, I called it a "silly" mistake, but note that it may well have been caused by the highly unusual combination of three subordinate clauses in one main clause. Actually, the student was probably trying for four subordinate clauses -- "The worst day [I spent] was [when my momy told me [my aunt died] and [*that I* had to go to school]]." For a fourth grader, that is a very big stretch.