• This lesson is aimed at 5th-6th grade students
• Can be used to supplement any of the Earth Science Content kits, such as: Water
• Creates links to math skills
• Takes approximately 3 to 4 class sessions to complete
• Students will be using science notebooks. To learn more, go to http://www.sciencenotebooks.org
• This lesson is also available in PDF. Click here to download.

• Tides occur in cycles that can be predicted by studying their patterns.

• What are tidal patterns?
• Why might it be helpful to be able to understand and predict tidal patterns?

Science 1.2.4 Components and patterns of Earthís Systems: Understand that Earthís system includes a mostly solid interior, landforms, bodies of water, and an atmosphere. W
Science 2.1.1 Questioning: Understand how to ask a question about objects, organisms and events in the environment. W
Science 2.1.3 Explaining: Apply understanding of how to construct a scientific explanation using evidence and inferential logic.
Science 2.1.5 Communicating: Understand how to report investigations and explanations of objects, events, systems, and processes. W
Math 2.2 Constructing solutions: select and use relevant information to construct solutions W
Math 3.1 Analyze information: analyze numerical, measurement, geometric, and/or statistical information in familiar situations W
Math 3.2 Conclude: draw and support conclusions W
Math 4.1 Gather information: understand how to develop and follow a plan for collecting numerical information W
Math 4.2 Organize, represent, and share information: to communicate a given purpose W

• There is only one high and one low tide each day (there are often two high tides and two low tides each day, known as a semi-diurnal tide)
• High and low tide occur at the same time every day (high and low tide times change)
• Tides are random and unpredictable (tides have predictable patterns that can be studied)

• notebooking
• orally launching the “big idea”
• modeling how to read a tide chart
• students decipher a tide chart and graph data
• students draw conclusions from their graphs
  
  

This lesson focuses on the Puget Sound Tidal System

The important structures are:

• The moon, sun, and earth
• Ocean

Energy Transfers:

• Motion of one body of water transfers to another

Forces acting on the system:

• Gravity of the sun and moon act upon tides
• Gravity and centrifugal force of earth act on tides
• Push of current and friction affect water movement

• Student journals, graphs, written graph observations, and data conclusions
  
• Post-lesson quiz (see end of document.)

Teacher:

• Transparencies or other means of projecting graph paper http://www.padillabay.gov/lessons/graph.pdf and a single page of a tide chart (from a grocery or sporting goods store, phone book or the Internet) http://tidesandcurrents.noaa.gov

Per Student:

• notebook
• pencil
• tide chart
• 1/2 cm graph paper http://www.padillabay.gov/lessons/graph.pdf
• ruler
• quiz (at the end of this lesson plan)

Pre-Lesson Preparation/
Teacher Background Information

1. Locate local tide tables for each student. They can easily be found on-line at, link: (go to “tide predictions ” then select your state and click “predictions” for the location closest to your school.)
2. To find out more about tides, click here:
http://estuary-webquest.tripod.com/id13.htm
3. Look through the tables to familiarize yourself with how to read it. Notice that there are two high and two low tides a day, but one of the high tides is higher than the other, and one of the low tides is lower than the other.  Sometimes there will be a diurnal tide, only one high and one low tide in a day. This occurs because the tidal cycle is actually 25 hours.  Also, sometimes high and lows are so close in height, it seems as if there’s only one high and one low.


From: http://www.geo.arizona.edu/Antevs/ecol438/tides02.jpg

4. In the US, the zero measurement is set at the average of the “low-lows.”  Thus, negative tides are possible.  Also, the tides are given in decimal feet, not feet and inches. Thus, 12.5 means 12’+1/2’ + 12’6”.  In Canada, zero is set at the lowest tide ever. Therefore, negative tides are not possible. 
5. Study the table and find a seven-day period you want the students to graph, preferably the most current week. These dates will be on your horizontal axis along with time. Notice the height of the tide in decimal feet. This will be the range for your vertical axis. If your students have not had much graphing experience this year, you may want to pre-write the time and date labels on the graph paper for them.
6. The graph the students are making should look as described below: See the link for an example: http://www.padillabay.gov/lessons/example.pdf
   
   • Use an 11 by 17 inch graphing paper (see Materials for link) with 0.5 centimeter grid, horizontally located.
     
   • You should make a four square-spaced margin on both the vertical and horizontal axis. Starting at the far left hand side not including the margin, count off eight squares to the right and then draw a vertical line to make the first column.
     
   • Continue this until you have seven columns (there will be some extra space on the right side.)
     
   • Next, each column needs to have 24 hours represented. The best way to do this is to show where the 12 o’clock and 6 o’clock (both A.M. and P.M.) times occur and then the students can estimate where the actual time would be as they are graphing. Starting on the first vertical line, put a 12, count two squares and put a 6, continue across the columns.
     
   • Each column should also be dated for the 7 days you plan to graph. 
     
   • Next, the vertical column should be labeled 1 foot per two squares. Start with -4 feet and go up to about 12 feet, don’t forget about zero. (You may need to change this slightly depending on what kind of tidal range you have in your area.)
     
   • Next, you can begin plotting dots for each day as the data reads from the NOAA website. http://tidesandcurrents.noaa.gov
     
   • You should write in the times and heights with each point. 
     
   • Connect the points with lines. See the attached example: http://www.padillabay.gov/lessons/example.pdf

1. Start by introducing a tide table. Explain to students that NOAA and other organizations publish these tables and are constantly up-dating them in order to let people know when the tides are going to be at their highest and lowest.
2. Ask students to independently journal about why being able to predict tides would be important. Some possible probing questions are:
   • Who would need to know when tides are going to be high or low?
   • Think of one profession or hobby that can best be performed during high tide, and one that can best be preformed during low tide.
   • Why would you want to know when tides are going to be high or low?
   • Briefly have students share their responses either in a class discussion, or with a partner.

1. Ask students if they have ever seen or used a tide chart before.
2. Tell them that today will gathering data from tide tables, graph the data, and look for patterns in order to draw conclusions about the predictability of tides.
3. Pass out tide tables (from the NOAA website) to the students, project yours if you have a document camera.
4. With everybody looking at the same set of date, tell the students how to read the table. You should point out features such as locating the month, the date, day of the week, time of year, etc.
5. Tell students that you are going to show them how to graph some of the data from the table.  Use another set of days to graph as an example. (In the interest of time, you may want to use a shorter set of days…like four or five.) Tell them that you are going to put the dates and time in the columns along the horizontal axis. Ask for thoughts on what you should put on the vertical axis. (The height of the tides.)
6. After you have graphed the data, point out the following tides: high-high (highest tide of the day), low-high (lower high tide of the day), high-low (higher low tide of the day), low-low (lowest low tide of the day). This is for the semi-diurnal tides. Point out the high tide and low tide if you have diurnal tides.     
7. Tell students that having just a graph is not enough. Scientists also have to write a description of the patterns they see and conclusions they can draw from these patterns.  Model through a think-aloud what patterns you notice in the shape of the data. Write this down.
8. Pass out the 11x17 graphing paper (use pre-labeled paper if your students are unfamiliar with creating their own graphs). Tell students that they are now going to work on their own graphing the seven-day period that you have assigned. Ask them which axis they should put the dates and time on (horizontal). Ask students what goes on the vertical axis.  (Height in feet) Give the range in feet you want them to start and end with. (Example: start with -4, end up with +12.) Remember to put one foot for every two squares, and don’t forget about zero.



From: http://www.globalsecurity.org/military/library/policy/army/fm/55-501/image1553.gif

9. Students should put a title on their graph and label the vertical and horizontal axis.
10. Have students graph and then describe the shape of their data. Have them write down patterns they see in the following tides:    high-high, low-high, low-low, high-low
11. Students should label each data point with the exact time and height of the tide.  Ask them to come up with conclusions about their data.

1. Ask students to share their written comments on the graphing data pattern and conclusions.
2. If it does not come up, tell students that Due to the moon, tides occur in a 28-day cycle and therefore advance a little less than an hour a day in order to get back their where they started over that period of time.

• Have struggling students work in a small group with you on the independent activity, or with a partner. Have high achieving/quick finisher students graph both of the daily low tides over a 6-day period in one location. Make sure that they choose days that have two low tides each day. They should use different colors for the low-low versus the high-low. Have them write down their observations about the patterns in the of the graphs


-or-
• Have high achieving/quick finisher students graph both of the daily high tides over a 6-day period in one location. Make sure that they choose days that have two high tides each day. They should use different colors for the high-high versus the low-high. Have them record their observations about the patterns of the graphs.

1. Does the low-low tide stay the same each day of the week? If yes, explain why you think this is. If no, record the approximate time difference and explain why you think this is. Are your results the same for the 3 other types of tides?

2. Youíre going to Port Townsend for outdoor school in 3 days. Today the lowest tide is at 3:30 AM. At approximately what time will low tide occur when youíre there? Explain how you know your approximation is reasonable. Hint: use your results from question number one.

1. No, it changes about 40 minutes later each day. Answers may very: logical predictions including the moon, the moon rising later, and the earth rotating would be good predictions. This is the same for all four of the tides: high-high, low-high, high-low, and low-low.

2. Low tide will occur at 5:30 AM. Each day low tide occurs on average 40 minutes later than the day before. Three days from now will be 3x40=120 minutes later than 3:30AM, which is the same as 2 hours later.