When/While/As I was having supper, Tom visited me.

[Alice Chu]

Please tell me if my understanding is correct.
1) When/As Tom visited me, I was having supper.
2) When/While/As I was having supper, Tom visited me.
3) When/As Candy finished her work, she had some snacks.
4) While Lisa was cooking, Joe was reading a newspaper.
5) While Joe was reading a newspaper, Lisa was cooking.
“While” can’t be replaced with “as” or “when” in sentence 4 and 5.
“While” can’t be used in sentence 1 or 3.

 

[jutfrank]

“While” can’t be replaced with “as” or “when” in sentence 4 and 5.

You can do the replacement, but of course you'll change the sentence. Why would you want to do that?

“While” can’t be used in sentence 1 or 3.

That is right.

Where did you get these sentences from?

You will be better off studying the uses of each word separately. Why have you included multiple options in sentences 2, 3, and 4? You appear to be under the impression that they're interchangeable in meaning. You should understand that if you replace one word with another, you invariably change the meaning.

 

[Alice Chu]

I wrote the sentences.
I need to make sure which answers are possible when giving my students tests about when, as and while.
Are the two sentences below incorrect?
As Lisa was cooking, Joe was reading a newspaper.
When Lisa was cooking, Joe was reading a newspaper.

 

[jutfrank]

I need to make sure which answers are possible when giving my students tests about when, as and while.

I don't think that's really what you need. You need to teach the differences of use between these words before you test your students.

I suggest you teach these words separately, because it's easy to get confused between them. In some cases, some of these words can be near interchangeable, but in other cases, the meanings can be wildly different. Make sure you use examples that show the differences, not the similarities.