También asegúrense de que todos a visitar los museos. a. van b. vayan c. pongan

This sentence stands for the subjunctive mood. We use the subjunctive to express desires, doubts, the unknown, the abstract, and emotions. As in the indicative, the subjunctive mood includes the same verb tenses, including the perfect, the past, and the future. Subjunctive sentences often have parts linked by a relative pronoun (que, quien, como). This sentence uses the pronoun que. Finally:

También asegúrense de que todos vayan

So vayan is the conjugation of the irregular verb ir that matches the third person plural in the subjunctive mood.

cuando era un niño durante el verano salía a jugar con mis mejores amigos, ¿verdad?