9781422283363

WORDS TO UNDERSTAND

calendar —a document that shows the days, weeks, and months of a year.

diary —a book in which a person keeps a daily record of events and experiences.

digital —a clock or watch that shows the time by means of numerical digits rather than hands or a pointer.

RESEARCH PROJECT One of the earliest timekeeping devices is a water clock, which used water dripping at a constant rate in order to mark periods of time. Visit the Science Buddies website (www.sciencebuddies.org/science-fair-projects/project_ideas/ApMech_p047.shtml#summary) and follow the instructions on how to make a water clock.

TEXT-DEPENDENT QUESTIONS

1. What do we use time for? 2. What do calendars measure?

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