Fill in each blank with the correct word from the lesson.

1. A quartz watch counts the vibrations of a quartz crystal — thirty-two thousand seven hundred and sixty-eight times per _______.
2. Humans have been _______ time for at least five thousand years.
3. _______ic clocks count atomic vibrations and are accurate to within one second over three hundred years.
4. Measuring Time is an important topic in _______.
5. We can learn about _______ from this lesson.

Choose the best option for each question.

1. What does the period of a pendulum depend on?
   a) Weight of the bobb) Angle of swingc) Length of the pendulum onlyd) Material of the bob
2. What is the SI unit of time?
   a) Minuteb) Hourc) Secondd) Millisecond
3. How do all clocks work?
   a) By using gravityb) By counting a regular repeating eventc) By measuring temperatured) By counting light waves only

Write T for True or F for False in the brackets.

1. Length of the pendulum only is one of the key concepts in the lesson on Measuring Time.
2. Weight of the bob is the main topic of this lesson.
3. A quartz watch counts the vibrations of a quartz crystal — thirty-two thousand seven hundred and sixty-eight times per second.
4. A quartz watch counts the vibrations of a quartz crystal — thirty-two thousand seven hundred and sixty-eight times per Minute.

1. In your own words, explain what Measuring Time means.
2. List two things you learned from this lesson on Measuring Time.