Just out of curiosity, is it okay to use the phrase "and so" in a sentence? Like "Johnathan knew that he had to help the boy asking a question on Jiskha. And so, he did just that, and the boy went on to being the happiest boy on earth."

I just need to know if "and so" is a proper introductory element.

In casual writing, I think "and so" is okay. In more formal writing, I might prefer "therefore", or "as a result", or merely, "so".

In any case, it really isn't necessary at all. The sentence could begin, "He did just that..."

Alright, thanks!

You're welcome. Keep in mind that other tutors/teachers might have a different "take". It used to be that beginning a sentence with a conjunction ("and", "but", etc.) was considered bad grammar. Now it's more acceptable. I still think the "and so" is unnecessary.

Yes, "and so" is a proper introductory element that can be used in a sentence. It is commonly used to indicate cause and effect or to show a logical progression of events. In the example sentence you provided, "And so" is used to indicate that Johnathan's decision to help the boy was a result of his understanding of the situation. It helps connect the two clauses and convey the cause and effect relationship between them.

To determine whether or not "and so" is appropriate to use in a given context, it can be helpful to consider the flow and coherence of the sentence. Ask yourself if using "and so" accurately reflects the relationship between the two clauses and if it enhances the overall meaning of the sentence. In general, it is acceptable to use "and so" as an introductory element when it appropriately fits the context and adds clarity to the sentence.