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Activity: Tide Prediction
NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas
Table of Contents


  • Table 6.2
  • Fig. 6.14
  • Fig. 6.15
  • Pencil




  1. From the tide data in Table 6.2 make a tide graph showing high and low tides.
    1. From Table 6.2, determine the time and tide height for the first high tide on Thursday, July 8.
    2. Plot this as a data point on the tide graph in Fig. 6.14.
    3. Repeat steps (a) and (b) for the remaining high and low tides on July 8.
    4. Plot the tide information for the rest of the week as data points in Fig. 6.14.
  2. Connect the points on the graph. Because the tide level changes gradually, draw a smooth, curved line between the data points.


Activity Questions
  1. Use your tide graph to determine the day with the largest tidal range.
    1. On what day did it occur?
    2. What was the range (in ft)?
  2. Find the day with the smallest tidal range.
    1. On what day did it occur?
    2. What was the range (in ft)?
  3. Recall that a flood tide is a rising or incoming tide between low tide and high tide. An ebb tide is a falling or outgoing tide between high tide and low tide. On what days and times do you expect the
    1. strongest flood tide?
    2. weakest flood tide?
    3. strongest ebb tide?
    4. weakest ebb tide?
  4. Why do you think Thursday, July 8, and Wednesday, July 14, only have three tidal heights?
  5. Draw the location of the moon in relation to the earth and the sun on Sunday, July 11. How do you think the moon phase affected the tides?
  6. How do you think the tides will be different on July 18? Draw the location of the moon in relation to the earth and the sun on July 18.
  7. Assume that you live on the shore of a bay that is 20 ft deep at high tide. The entrance to the bay is over a rocky ledge, which is only 10 ft deep at high tide. The tidal range is 4 ft.
    1. What would be the depth of the bay at low tide?
    2. What would be the depth over the rocky ledge at low tide?

Fig. 6.15. Aerial photograph of Hilo Bay, Hawai‘i

Image courtesy of Kanoa Withington, Wikimedia Commons

  1. The average tidal range in Hawai‘i is 1 m (approximately 3 feet). Hilo is a small funnel-shaped bay on the Island of Hawai‘i (Fig. 6.15). How do you think the shape of Hilo Bay affect its tidal range compared to other areas in Hawai‘i?
  2. You are piloting a fishing boat with your grandfather and want to go to the fish market dock in Hilo Bay on July 10 to unload your fresh fish. The fish market opens early and your fresh fish can only be unloaded between 3 a.m. and 5 a.m. Your fully loaded boat draws 3 meters (depth below the waterline). The water under the fish market dock is 7 feet deep at 0 tide level. Are you able to deliver your fish on time on July 10? Why or why not?
  3. You are in charge of planning a two-hour-long field trip to a rocky shoreline area with tidepools that are exposed only during minus tides. You have only one hour before and after the low tide to explore the tidepools. Which would be the best day for the field trip? Explain your choice in detail.
  4. You may have noticed that throughout Exploring Our Fluid Earth all measurements are in metric units, except for the tide table for Hilo Bay (Table 6.2). The metric system is not only the most common measuring system in the world, it is also the standard system used in science. However, in Hawai‘i and much of the United States, tide tables are published in feet. Is one choice of unit better than the other? Explain your reasoning.
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.