How can you tell when to use the subjunctive versus the indicative when the main clause beings with dijo que.?

Question

Por ejemplo...

Nos dijo que compraramos...versus...
Dijo que estudio en la escuela.

Answer 1

Use the subjunctive in this construction when you are reporting a command or request.
For example, "Nos dijo que compraramos unos huevos." would be translated as "He told us to buy some eggs."

Use the indicative when you are reporting the person's statement of a fact: "Nos dijo que estudió en la escuela" -> "He told us that he studied in school."

Notice that English does this in a slightly different way, by using the "to" construction for commands/requests and the "that" construction for reports of statements.

Answer 2

Hello there..
The basic difference between subjunctive and indicative is that the first one its placed when expressing a wish, a desire a possibility that its not yet a fact and the indicative its something for sure.
Usually the subjunctive goes after the connector "que" so in your case.. "nos dijo QUE compraramos (verb in subjunctive)" . If it were indicative it would have been "nosotros compramos". Its a very little difference in the expression itself when its "he told us to buy it" and "we buy it" its the "que" that makes all the trouble.
On your "dijo que estudio en la escuela" its the same case, the verb before the "que" its always subjunctive.
However in this circunstances you used first the verb "decir" (dijo) wich is an indicative. If it were subjunctive it would be put like this "nosotros pensamos que dirias eso" (we thought that you would say that)
Other examples:
"que hablara con su novio fue lo mejor"
(to speak with his bf was the best thing to do)
"ella confesó que viviría por mucho tiempo"
(she confessed that she would live for a long time).

Subjunctive and Indicative differences are always a little tricky, dont get to desperate, you will get it on practice.
Good luck!