Introduction
Have you ever built a sandcastle on the beach in the morning, only to come back in the afternoon and find it swallowed by the sea? Every day, without fail, the ocean rises and falls along our coastlines — sometimes twice, sometimes even more. Fishermen time their trips around it. Ports schedule ships around it. Coastal communities plan their entire day around it. But what actually makes the ocean move like this?
In this WebQuest, you'll take on the role of a junior oceanographer assigned to explain this phenomenon to your local community. By the end, you'll not only understand why tides happen — you'll be able to read a real tide chart and predict what the ocean will do next.
Task
Working in small teams, you will research the causes of ocean tides and produce an Illustrated Tide Explainer — a short presentation (poster, slide deck, or infographic) that:
- Explains, in your own words, how the gravitational pull of the moon and sun causes tides.
- Illustrates the difference between spring tides and neap tides.
- Reads and interprets a real tide chart for a Philippine coastal location.
- Explains one practical reason why knowing tide times matters for your community (e.g., fishing, transportation, safety).
Process
Step 1: Form your team (3–4 members). Assign roles: Researcher, Illustrator, Data Analyst, Presenter (roles can overlap in smaller teams).
Step 2: Visit the resources listed below and, as a team, answer these guiding questions in your notebook or shared document:
- What causes the "bulge" of water on the side of Earth facing the moon — and why is there also a bulge on the opposite side?
- What is the difference between a spring tide and a neap tide, and when does each occur?
- What is a tide chart, and what do the numbers and times on it represent?
Step 3: Using the PhET simulation, experiment with moon position and observe how the tidal bulge shifts. Record at least two observations.
Step 4: Choose a coastal town or city in the Philippines and pull up its tide chart for the current week using the NOAA or PAGASA resource. Identify the times of high and low tide for one full day.
Step 5: Design your Illustrated Tide Explainer, incorporating your research, your simulation observations, and your tide chart reading.
Step 6: Prepare and rehearse your 5-minute team presentation.
Step 7: Present to the class and submit your explainer for evaluation.
Evaluation
| Criteria | Excellent (4) | Good (3) | Developing (2) | Beginning (1) |
|---|---|---|---|---|
| Explanation of Tidal Cause | Clearly and accurately explains gravitational cause of tides, including both near and far bulges | Explains gravitational cause with minor gaps or unclear points | Attempts explanation but contains a scientific misconception | Explanation is missing or largely inaccurate |
| Spring vs. Neap Tides | Clearly distinguishes both types with correct timing/alignment | Distinguishes both types with minor errors | Only partially distinguishes the two | Not addressed or incorrect |
| Tide Chart Reading | Accurately reads and reports high/low tide times with correct interpretation | Reads chart with one minor error | Reads chart with several errors | Unable to read the chart correctly |
| Real-World Relevance | Gives a clear, well-reasoned practical application | Gives a relevant but under-explained application | Application is vague or weakly connected | No real-world connection given |
| Presentation & Teamwork | All members contribute; presentation is clear, organized, and within time | Most members contribute; mostly organized | Uneven participation or disorganized delivery | One member does most of the work; unclear delivery |
Conclusion
CONCLUSION
By completing this WebQuest, you've moved from simply observing that "the ocean goes up and down" to understanding the actual physics behind it — the gravitational dance between Earth, the moon, and the sun. You've also practiced a skill scientists and coastal communities use every day: reading real data to make predictions about the natural world.
Take a moment to reflect: How did working through the simulation change or confirm what you already believed about tides? Where might you see this kind of gravitational relationship at work elsewhere in the world around you?