Clearly articulate classroom rules about talking and reiterate these rules to students as frequently as needed. If necessary, remind students each morning that they are not permitted to talk during class and that they should save chatter for breaks and recesses. Young students at the first-grade level do not always have strong memories, so you will need to reinforce classroom rules often.
Reinforce rules about not talking during class by making posters and hanging them around the classroom. Visual aids will help students to internalize the rules. Also assign students the project of making their own poster. Tell students to write the rule on the poster and draw an illustration to correspond with it.
Reward students who respect the rules. Throughout the day, give students a point if you catch them talking out of turn. At the end of the week, reward students with fewer than three points with a homework pass, an extended recess, a sticker or eraser, or some other small prize. This system will motivate students to make an effort not to speak out of turn during class.