Before class begins, students should clear their minds so that they are ready to learn. To clear one's mind and look inward in silent contemplation is called mokuso (黙想). Here is a nice article written by Furuya Sensei about the need to be in right mindset in order to learn.
Look & Listen by Rev. Kensho Furuya
Nowadays, I don't think there is anything more important in practice than to look hard and listen carefully. One must not only focus on their teacher but also be aware of everything around that is happening in practice and in the dojo which might be related to practice. When it comes to idle gossip and chit-chat, just run away as fast as you can! But even the slightest hint of instruction, clue or hint to improve your practice, catch it right away and don't lose it or forget it!
This is a very important skill to develop, not only for one’s Aikido, but in every aspect of daily life.
More often than not, people do not understand because of what they are hearing or seeing is too difficult to understand. This is merely because they are not listening closely enough or seeing hard enough. Much of the time, we are so filled with our own ideas and conclusions that there is no room in their heads for anything else. Much of the time, however, we are just not there in the present. Many times, good Aikido is just the result of paying attention and following the instructions and practicing earnestly, sincerely and with awareness.