Tides

Engage

10 Minutes

Ask the students what they know about tides, and begin a KWL chart. Explain that you will be looking for the answers to these questions, as well as other questions they raise about tides:
How are waves and tides related? What are tides? What causes tides? What does wave energy have to do with tidal motion?

Explore​

20 Minutes

Project the NOAA Tide tutorial and work through it with students, providing guidance and discussing the concepts. Be sure to show the animation. (The reading level of the tutorial is high for most middle school students, so this may not work well as an independent assignment.)

Explain

30 Minutes

Have students work in groups of 2-4 to discuss the important ideas, facts, and answers to the focus questions. They should work together to choose a format and create a graphic organizer that shows the important ideas, facts, and answers to the questions: What are tides? What causes the tides? How are waves and tides related? Each student should glue a copy of the graphic organizer into their science notebook.

Have groups share their graphic organizers, and complete the KWL chart about tides as a class. Students should add any ideas or facts they may have missed to their own organizer in their science notebook.

Important concepts listed should include the following:
•    Tides are regular and predictable.
•    Tides are very long-period waves that start in the ocean because of the forces of gravity from the sun and moon, and move toward coastlines.
•    Tides appear on coastlines as the regular rise and fall of the sea surface. Low tide on shore coincides with the wave trough, and high tide corresponds with the wave crest.
•    Incoming (flood) and outgoing (ebb) tides can create horizontal movement of water or currents. Tide currents can be strong in entrances, inlets, and narrow straits. They are weak in the open ocean.

Elaborate

 This activity is expanded on in the following activity, Tide Patterns.

Curricular Connections

This investigation can provides connections to math through graphing activities and measurements and calculations of wave frequencies and periods. The many opportunities to write, discuss, and present information to the class provide connections to language arts.

Ideas for adapting to different local environment or context. Investigate local cultural traditions and knowledge related to tides.