1st Conditional

1- Structure

You can use conditionals in two orders:

Order 1   (a comma between the two parts)
                          Situation                                Consequence
               IF + SUB+ VERB PRES SIMP        SUB + WILL + VERB INFINITIVE
                          If I walk slowly,                    I Will arrive late
                          If you don't listen,                  you won't learn
                                 

Order 2      (no comma between the two parts)            

                        Consequence                           Situation
          SUB + WILL + VERB INFINITIVE       IF + SUB+ VERB PRES SIMP
                         They Will miss the bus          if they don't hurry
                         she won't pass the exam         if Sally watches TV

* the IF PART indicate the condition (lo que se debe cumplir)
* the OTHER PART expresses the consequence or the effect of the condition

2- Use
 -We use 1st conditional to talk about probable future actions ( que ocurrirán casi seguro si se cumple la condición)
*We also can create 1st Conditional sentences with WHEN and UNLESS
-WHEN I know, I Will tell you
-UNLESS you study more, you won't pass the exam