Tides

CE14 Tides: Unit of Study: Changing Earth
Lesson Title: Tides

**Essential Question(s):**
 * How does the study of properties and patterns help us to understand the natural world?
 * How do models help us understand systems?

**TEKS:**
 * ===== 4.3C Represent the natural world using models such as rivers, stream tables, or fossils and identify their limitations, including accuracy and size. =====
 * ===== 4.8C Collect and analyze data to identify sequences and predict patterns of change in shadows, tides, seasons, and the observable appearance of Moon over time. =====

**Learning Objective:**
 * ===== Students will collect and analyze data to identify sequences and predict patterns of change in tides. Students will use content-based vocabulary in speaking and writing about their understanding of tides. =====

**Evidence:**
 * ===== Students will draw a diagram of the earth and moon positions to represent high and low tides. Students will predict patterns of change in ocean tides. =====

**Pre-assessment:**
 * Students will discuss what they know about why, how, and when the level of oceans rise and falls each day.

**Procedure:**

**Activity 1 Part 1: What Causes Tides?**

 * What causes the tides (the rise and fall of the oceans every day)?
 * Teachers ask the students why they think tides occur (See Background Knowledge).
 * As a class, view the video about tides. Students will work with a partner to discuss interesting facts in the video.

**Discovery Education Streaming Video: A Closer Look at Space: Tide Segment.**

**Activity 2 Part 1: Examining A Tide Chart**
 * ==== Examine the table containing the times of low and high tides on the Atlantic coast from April 10-14 and the table containing the times of low and high tides in Corpus Christi for the same time period. Have students work in groups to answer questions about the tide tables. ====
 * ==== Approximately how much time passes between each high tide and low tide? Approximately 6 hours ====
 * ==== How many high and low tides usually occur during a 24-hour period? Two high and two low ====
 * ==== Do the high and low tides happen at the same time every day? No ====

**Activity 2 Part 2: Predicting the Tides**
 * ==== Predict the times for the high and low tides for the next day for each location. ====
 * ==== Students draw and complete the Prediction Chart in their science notebooks. ====
 * ==== Have students share predictions with other groups and discuss the reasons for their predictions. ====

**Considerations for Differentiation:**
 * Allow the students to use a paper clock that the hands can be moved easily to show 50-minute intervals.
 * Students work in pairs for the predictions.
 * Students can use the website of actual tides to collect data and make predictions: http://www.mobilegeographics.com:81/locations/545.html

**Materials:** Atlantic Coast Tide Chart, Corpus Christi Tide Chart, and Prediction Chart [|tides.pdf]

**Background Knowledge:**
 * What causes the tides (the rise and fall of the oceans every day)?
 * "Tides" refers to the alternating rise and fall of sea level within a day. What causes the sea level to change? It is actually the gravitational attraction of the sun and moon that cause waters of the ocean to swell and recede at different parts of the earth.
 * Why does Earth experience high tides on the opposite side at the same time?
 * The earth and the moon are two great masses that have a significant gravitational pull on each other. This is what keeps the moon in orbit around the earth, and it is also what causes tides to occur in the ocean. Picture the earth with a uniform level of water all around it. The moon’s gravity pulls on the earth, and pulls the water towards it. The water moves up into a slight bulge on the side of the earth that faces the moon. (At the same time, there is a force pulling water out in the opposite direction of the moon.) The moon causes the water to bulge towards the moon and the earth to move slightly towards the moon. This causes water on the far end of the earth, away from the moon to bulge. See Discovery Streaming Video:
 * A Closer Look at Space: Tide Segment
 * In reality, the Earth’s landmasses and ocean depths also have an effect on how high and low the tides are during the Earth/moon cycle. This is why some areas of our oceans experience different levels of high and low tides during different days in the cycle.

**Resources:** The tide charts are adapted from Beverly, Massachusetts Tidal Charts. Short clip about tides www.onr.navy.mil/Focus/ocean/motion/tides1.htm Tides NOAA: http://oceanservice.noaa.gov/education/kits/tides/tides02_cause.html Webquest about what causes tides: www.internet4classrooms.com/tide.htm Lesson Adapted from Tide Activity; http://www.mrconant.org/webquests/tides/tides.htm  ==**[|Tides Video] ** ==