Be on the lookout
Many students think that if they are using an RCX Sensor Watcher, their program is set to check the message repeatedly. They are right to a certain extent—a sensor watcher does check for messages repeatedly. What they sometimes forget, however, is that there’s already a message stored in its memory and that it can’t receive a new one until the old one is cleared.
What you can do: Use the container analogy described in the Discussion Points section.