Offers an introduction to the concept of time, covering timekeeping tools including calendars, clocks, and watches.

Examines different aspects of time and how we measure it, including seasons, sundials, clocks, local and Greenwich mean time, the prime meridian, time zones, atomic clocks, months, years, and more.

Find out what causes the seasons and how they affect living things, from people to plants.

Explains how the rotation of the Earth causes the cycle of day and night.

To the naked eye, the most evident defining feature of the planets is their motion across the night sky. It was this motion that allowed ancient civilizations to single them out as different from fixed stars. “The Observer’s Guide to Planetary Motion” takes each planet and its moons (if it has them) in turn and describes how the geometry of the Solar System gives rise to its observed motions. Although the motions of the planets may be described as simple elliptical orbits around the Sun, we have to observe them from a particular vantage point: the Earth, which spins daily on its axis and circles around the Sun each year. The motions of the planets as observed relative to this spinning observatory take on more complicated patterns. Periodically, objects become prominent in the night sky for a few weeks or months, while at other times they pass too close to the Sun to be observed. “The Observer’s Guide to Planetary Motion” provides accurate tables of the best time for observing each planet, together with other notable events in their orbits, helping amateur astronomers plan when and what to observe. Uniquely each of the chapters includes extensive explanatory text, relating the events listed to the physical geometry of the Solar System. Along the way, many questions are answered: Why does Mars take over two years between apparitions (the times when it is visible from Earth) in the night sky, while Uranus and Neptune take almost exactly a year? Why do planets appear higher in the night sky when they’re visible in the winter months? Why do Saturn’s rings appear to open and close every 15 years? This book places seemingly disparate astronomical events into an understandable three-dimensional structure, enabling an appreciation that, for example, very good apparitions of Mars come around roughly every 15 years and that those in 2018 and 2035 will be nearly as good as that seen in 2003. Events are listed for the time period 2010-2030 and in the case of rarer events (such as eclipses and apparitions of Mars) even longer time periods are covered. A short closing chapter describes the seasonal appearance of deep sky objects, which follow an annual cycle as a result of Earth’s orbital motion around the Sun.

Many K–6 teachers--and students--still think of mathematics as a totally separate subject from literacy. Yet incorporating math content into the language arts block helps students gain skills for reading many kinds of texts. And bringing reading, writing, and talking into the math classroom supports the development of conceptual knowledge and problem solving, in addition to computational skills. This invaluable book thoroughly explains integrated instruction and gives teachers the tools to make it a reality. Grounded in current best practices for both language arts and math, the book includes planning advice, learning activities, assessment strategies, reproducibles, and resources, plus a wealth of examples from actual classrooms.

An exploration of the history and science of timekeeping, from the earliest sundials to the latest atomic clocks. The book describes various methods and devices used to measure time, including mechanical clocks, water clocks, and astronomical observations. The author also explains the principles behind modern time standards like Greenwich Mean Time (GMT). This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.