Sequence of tenses

On my grammar book, it says: When the verb in the main clause is in the past or past perfect tense, the verb in the subordinate cluase must also be past or past perfect. Here is the example: The researchers discovered that people varied widely in their knowledge of public events.  the first verb in its past form is in the main clause, and the second verb is in the subordinate clause. If i want to say a sentence: I was going to say that when I went(go)? to school every day, ……. Here should i say 'go to school' or 'went to school'? because i mean i go to school every day, which is present tense, but since i used past tense in the main clause, so what can i do?

But the contradicted thing is on my book, it also says that the tenses need no be identical as long as they reflect changes in actual or relative time. Here is the example: Ramon's father arrived in the USA thirty years ago, and now Ramon has decided that he will return to his father's homeland.   If according to what i first said that past vs. past, then 'has decided' is in the present perfect form which is not right? and 'will return' in this example should be converted to 'would return' because of the past tense in the main clause 'arrived'. but since it said tenses needed not to be identical, so it's in future tense.

I was deeply confused about these two. Which is right? Past Vs past or as long as they reflect changes in relative time, it's okay>?  Hope you can patiently read through my problem and help me out. thank you.

Let me repeat a chart I drew in another post.

Present Point of View Tenses
........ have done ......... do/does .............will do .........
  Present Perfect           Present              Future of the Present

Past Point of View Tenses
........had done .........did ..............would do ..............
  Past Perfect           Past               Future of the Past

Using the correct sequence of tenses is a matter of staying within one of these two points of view as long as your story stays within that same point of view.  Your story is usually within the same point of view as long as you join the facts of the story by using subordinating conjunctions. 

However, you may change your point of view, and then stay within the other point of view.  Often, the change in viewpoint is done with the appropriate adverbs on different sides of a coordinate conjunction.

Note below how the adverbs thirty years ago and now change the point of view from the past point of view (PV2) to the present point of view (PV1).

Ramon's father arrived (PV2) in the USA thirty years ago, || and now Ramon has decided (PV1) that he will return (PV1) to his father's homeland.

In the past point of view you have arrived, a simple past, and in the present point of view you have has decided, a present perfect, and will return, a future (of the present).

CJ

CalifJim wrote:

I was going to say that when I went(go)? to school every day, ……. Here should i say 'go to school' or 'went to school'? The sentence is not complete and coherent enough to make an accurate judgment. You can say either of these: I was going to say that when I went to school every day, I always went by bus.  (All PV2.) I was going to say that when I go to school every day, I always go by bus. (Change from PV2 for the verb of reporting to PV1 for what is reported.) The change of viewpoint in the second sentence is common in these situations when you are reporting something.  It's often done like this when what you are reporting is still true or generally true. CJ

Thanks, CJ. I think I get what you tried to say.  Actually, you get my point that I usually prefer the second sentence because I think 'I go to school.' is still true, so I want to use present tense. Is that okay I use the first one? If I say in the past tense, will other people think I went to school every day by bus only happened in the past or still happens?

CJ, I took your advice, so now I capitalize 'I'. If I want to change my point of view,  must I use any adverbs or other words to indicate the time. For example, if I want to say: I thought you went to school every day, but you only go to school every tuesday. In the first main clause, I think I actually used the phrase 'every day', so can I use 'go to school' instead?

I meant could I say: I thought you go to school every day?   Is "every day" a phrase that can make me change a point of view from past to present? But in this kind of sentence, we usually put past tense verb after 'thought'. For example, I thought you bought a book.  So I am not sure if I can use present tense in the first sentence that I wrote. As I asked before, must I use any adverbs or other words to indicate that I want to change my point of view?