Present the first block to the student. You should sit side by side at a table. One by one, remove the cylinders from the block and place them in a random order on the table. Most Montessori experts recommend you do this without discussion or explanation. Once all the cylinders have been removed, you should silently and with the same degree of care and consideration replace them one by one in the block. If at any point in the lesson the child joins in, then he may be left to work alone. He can hold the cylinders any way he likes and place them wherever he wants. Allow him to use the lesson independently until he puts the lesson away of his own accord. You will resume the next day. If the child does not join in, you may decide whether to continue or simply stop once you have replaced all the cylinders and resume the next day based on your school's teaching standards and your knowledge of the child's learning tendencies and personality.
Demonstrate the proper ways to handle the lesson. As the child uses the lesson over the next few days, demonstrate how to properly manage the cylinders. For example, if the child is being noisy, you might say, "Listen, I can take all the cylinders out and put them on the table without making any noise at all. Can you do it?" If the child is not holding the cylinders by the knobs, then approach and say, "Look, you have two fingers and a thumb." Show the child the thumb and first two fingers on her hand. Tell him to use those two fingers and his thumb to pick up each cylinder.
Allow the child to repeat the exercise as often as necessary until he is able to place all cylinders back in the block in their proper positions. The exercise is self-correcting because if one cylinder is misplaced, at least one other will not fit back into the block. Working on his own will help the child learn to accurately judge size.
Help the child work through all four cylinder blocks. As the child becomes comfortable with the easiest block, allow her to work with the two simplest blocks, then add in the third block and eventually the fourth. Children should use one block at a time until they are comfortable with judging sizes, then they can use more than one if your school's Montessori curriculum permits.
Encourage the child to use these lessons on his own. The cylinder blocks should be kept in an easily accessible spot in the classroom and children should use them regularly. Some instructors do not bring the fourth block into the classroom until everyone is comfortable with the first three, but this is entirely up to you.