simultaneous - Refers to actions or events that are performed or experienced at the same time, without any time between them.

They made a simultaneous broadcast of the event across multiple time zones that allowed people from all over the world to watch it live.
impressionable - Easily influenced by somebody or something, usually due to being inexperienced or naïve.

Because children tend to be very impressionable, their use of the internet should be monitored, so that they are kept away form undesirble influences.