Tides are an excellent example of how the Earth is an interdependent system where one part of the system affects others. Tides on Earth are the result of gravitational interactions with the Moon and Sun. More information about the Earth-Moon-System can be found here.
PowerPoint. Click to download the MS Powerpoint file (7.2 Mbytes).
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Online lecture Click to view a streaming lecture (~35 minutes).
Microsoft Word Click to download a student Claim-Evidence-Reasoning assessment about tides.
Tides Around the World! In this activity, students plot tidal data for a 48-hour period for different locatons around the world. Students work in groups of 2-3 and plot the data for their assigned station. Then they compare the data for their location with others in a gallery walk. Students will observe that the tidal range and timing varies at different locations around the world. Whereas many classroom activities in Earth Science are based on modeling, this is an excellent opportunity for students to analyze and interpret actual data. PDF Microsoft Word
Answer key - plots of tidal data for all locations. PDF
Examples of completed graphs done by students for gallery walk. PDF (5.8 Mbytes)
A Month of Tides In this activity, student plot high and low tide data for a period of one month. Students can work individually or in small groups to plot the data. Students will observe that the tidal range varies throughout the month. In addition, they compare the tide data with data for the phases of the Moon. Students should make a connection between the occurrence of Spring tides during the full and new Moons and neap tides during the first- and third-quarter Moons. Whereas many classroom activities in Earth Science are based on modeling, this is an excellent opportunity for students to analyze and interpret actual data. PDF Microsoft Word
Example of completed graph from activity. PDF
Online Video and Media Resources
Spring Tide Time Lapse, Halls Harbour This time lapse video shows the tidal variation in Halls Harbour in the Bay of Fundy
Tides and Water Levels This online tutorial from NOAA provides a great introduction to tides and has good public domain illustrations.
Our Restless Tides This online tutorial from NOAA about tides is very comprehensive with more detailed information.
What Physics Teachers Get Wrong about Tides! This PBS Space Time video explains the origin of the Earth's two tidal bulges.
How Tides Work This short BrainStuff videodiscusses the origin of the Earth's tides.
Watching the Tides This KQED Quest video discusses the origin of tides and visits the tidal gague at Crissy Field that has been operating since 1854.
Tides Crash Course This PBS video provides an excellent video tutorial on the origin of Earth's two tidal bulges and how tidal forces are affecting the Earth-Moon system.
Can Coastal Tides Power America? This PBS Newshour examines the potential for underwater turbines to produce electricity from the oceans' tidal fluctuations.
Intertidal Zone and Sea Level Rise Ths PBS video examines hour the rise in sea level and increase in ocean temperatures is affecting organisms in coastal tide pools.
The Tides Explained by MinutePhysics This YouTube video from MinutePhysics explains the origin of tides on Earth.
Tides and Water Levels oceanservice.noaa.gov/education/tutorial_tides/welcome.html This online tutorial from NOAA provides a great introduction to tides and has good public domain illustrations.
Our Restless Tides tidesandcurrents.noaa.gov/restles1.html This online tutorial from NOAA about tides is very comprehensive with more detailed information.
NOAA Tides and Currents tidesandcurrents.noaa.gov/map/ This NOAA website provides realtime tide and current data for stations throughout the United States.
Obtaining Tide Gauge Data www.psmsl.org/data/obtaining/ This website from the Permanent Service for Mean Sea Level (PSMSL) provides monthly and annual tide gauge data for sites around the globe. This site provides evidence of the rise of mean sea level due to climate change.
California King Tides Project california.kingtides.net/ This website is for a collaborative organization consisting of bay and coastal orgainzations that focuses on king tides and their effects on California with rising sea levels. They organize king tide viewing events and host contributed photos of king tides from the public.
Tidal Curiosities scijinks.jpl.nasa.gov/tidal-curiosities/ This website from NASA provides some detail about peculiarities of tidal cycles on Earth such as why some regions experience only one tidal cycle per day whereas most coastal regions experience about two complete daily cycles.
NGSS Disciplinary Core Ideas
The topic of tides is not explicitly included in the Performance Expectations or Disciplinary Core Ideas in the Next Generation Science Standards. From the NGSS Framework (M.S. Space Science): “There is a strong emphasis on a systems approach, using models of the solar system to explain astronomical and other observations of the cyclic patterns of eclipses, tides, and seasons.” Tides are an excellent topic to illustrate the Crosscutting Concept on patterns where observable patterns in nature guide organization and classification and prompt questions about relationships and causes underlying them. In addition, the topic of tides have an important connection to Global Change since perigeal spring tides (King tides) are resulting in coastal flooding as sea level continues to rise.
ESS1.B: Earth and the Solar System The orbits of Earth around the sun and of the moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily changes in the length and direction of shadows; and different positions of the sun, moon, and stars at different times of the day, month, and year. (5-ESS1-2)
ESS1.A: The Universe and Its Stars. Patterns of the apparent motion of the sun, the moon, and stars in the sky can be observed, described, predicted, and explained with models. (MS-ESS1-1)
ESS1.B: Earth and the Solar System. This model of the solar system can explain eclipses of the sun and the moon. Earth's spin axis is fixed in direction over the short-term but tilted relative to its orbit around the sun. The seasons are a result of that tilt and are caused by the differential intensity of sunlight on different areas of Earth across the year. (MS-ESS1-1)
Common Scientific Misconceptions
Sea level is level and constant (this misconception is reinforced by common use of mean sea level as base for surveying).
Second tidal bulge (away from Moon) is due to Moon's reduced gravitational attraction.
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