{"id":3428,"date":"2026-06-25T04:19:37","date_gmt":"2026-06-25T04:19:37","guid":{"rendered":"https:\/\/www.workybooks.com\/blog\/?p=3428"},"modified":"2026-06-25T04:20:42","modified_gmt":"2026-06-25T04:20:42","slug":"what-causes-tides-a-middle-school-science-teaching-guide","status":"publish","type":"post","link":"https:\/\/www.workybooks.com\/blog\/what-causes-tides-a-middle-school-science-teaching-guide\/","title":{"rendered":"What Causes Tides? A Middle School Science Teaching Guide"},"content":{"rendered":"\n

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Ask a class of middle schoolers what causes tides and most will tell you the Moon “pulls the water up.” They are half right \u2014 and that half-right answer is exactly what makes tides such a rich topic to teach. The moment a student tries to explain why there are two<\/em> high tides a day, the simple picture falls apart, and real model-based reasoning has to take over.<\/p>\n\n

That is also why tides sit so neatly across two NGSS performance expectations. They are a cyclic pattern of the Earth-Sun-Moon system (MS-ESS1-1<\/strong>) driven entirely by the role of gravity (MS-ESS1-2<\/strong>). Teach them well and you are not just covering ocean science \u2014 you are giving students a clean case study in using a model to explain a repeating pattern. Here is a sequence that works in middle school science classrooms, along with the visuals and tides worksheets that make each step land.<\/p>\n\n

Step 1 \u00b7 The cause<\/span>Start with gravity and the near-side bulge<\/h2>\n

Begin where the physics begins. Gravity is a pull between any two objects, and it gets stronger the closer they are. The Moon pulls on the whole Earth, but it pulls hardest on whatever is closest \u2014 the ocean water on the side facing the Moon. That water piles up into a tidal bulge<\/strong>, and a coast sitting under it experiences a high tide. Students grasp this part quickly; it matches their intuition.<\/p>\n

\"Diagram<\/a>
Two tidal bulges line up with the Moon \u2014 one on the near side, one on the far side.<\/figcaption><\/figure>\n\n

Step 2 \u00b7 The keystone<\/span>Teach the far-side bulge carefully<\/h2>\n

This is the make-or-break idea, and it is where most resources wave their hands. There is a second<\/em> tidal bulge on the side of Earth facing away<\/strong> from the Moon. Students find this baffling: how can the farthest point from the Moon also be a high tide?<\/p>\n

The answer is comparison, not magic. The Moon pulls the solid Earth toward it more strongly than it pulls the far-side water, because the solid Earth is closer to the Moon than that water is. Earth gets tugged away from the far-side water and leaves it behind \u2014 a second bulge. Spend real time here; if students can explain the far-side bulge in their own words, they understand tides.<\/p>\n

Teaching tip<\/b>Have students draw the Earth, Moon, and three arrows of different lengths (long for the near water, medium for solid Earth, short for the far water). The “leftover” far-side water is the second bulge. Drawing the relative pulls beats any sentence you can give them.<\/div>\n\n

Step 3 \u00b7 The pattern<\/span>Two tides a day, fifty minutes later<\/h2>\n

Once the two bulges are locked in, the daily pattern falls out for free. Earth rotates once a day, so any coast sweeps through both<\/strong> bulges and both thin spots in between \u2014 about two high tides and two low tides every day. And because the Moon keeps moving along its orbit, Earth has to spin a little extra each day to catch up, so high tide arrives roughly 50 minutes later than it did the day before. That single fact connects tides back to Moon phases<\/strong> and sets up everything that comes next.<\/p>\n\n

<\/path><\/svg><\/div>\n\n

Step 4 \u00b7 Bring in the Sun<\/span>Spring and Neap Tides<\/h2>\n

The Moon causes most of the tide, but the Sun and Moon<\/strong> together decide how big it gets. This is the spring-neap story, and it ties tides directly to the phases students already know.<\/p>\n

When the Sun, Moon, and Earth line up in a row \u2014 at the New Moon<\/strong> and Full Moon<\/strong> \u2014 the Sun’s pull and the Moon’s pull work together. Their bulges add up and you get spring tides<\/strong>: the biggest tidal range<\/strong> of the month. About a week later, at the quarter Moon phases<\/strong>, the Sun and Moon pull at a right angle and partly cancel, giving the small range of neap tides<\/strong>. (Worth flagging the classic trap: “spring” has nothing to do with the season.)<\/p>\n

\"Two-panel<\/a>
Spring tides form when the Sun, Moon, and Earth line up; neap tides form when the Sun and Moon are at a right angle.<\/figcaption><\/figure>\n

Connecting spring neap<\/strong> patterns to the lunar cycle is the natural bridge from your Moon phases unit \u2014 students realize the same geometry that makes phases also sizes the tides.<\/p>\n\n

Step 5 \u00b7 Make it quantitative<\/span>Graphing tides turns the concept into data<\/h2>\n

Here is where tides become an NGSS data lesson rather than a vocabulary list. Give students a day of tide-height readings and have them plot tide height over time. The graph does the teaching: the two-high, two-low pattern they reasoned about in Step 3 appears as a wave they can measure.<\/p>\n

\"Line<\/a>
From the Graphing Ocean Tides<\/strong> activity \u2014 students plot the data, then read the period and the tidal range straight off the curve.<\/figcaption><\/figure>\n

Once the curve is drawn, students can find the time between high tides, calculate the tidal range<\/strong>, and compare a spring-tide day with a neap-tide day using real numbers. That is the data-analysis muscle MS-ESS1-1 is built on, and graphing tides<\/strong> is the single best way to exercise it.<\/p>\n\n

\"Graphing<\/a>

Featured resource<\/p>

Graphing Ocean Tides<\/h3>

A print-ready data activity: students plot a full day of tide heights, find the daily pattern, compare spring and neap ranges, and explain the 50-minute shift. Answer key with the completed graph included.<\/p>Get this activity<\/a><\/div><\/div>\n\n

Step 6 \u00b7 Lock it in<\/span>A cause-and-effect graphic organizer<\/h2>\n

Tides are a causal chain \u2014 gravity, then two bulges, then rotation, then two tides a day \u2014 which makes them perfect for a graphic organizer. Asking students to fill the chain in their own words is the fastest way to surface who still cannot explain the far-side bulge.<\/p>\n

\"How<\/a>
The How the Moon Makes Tides<\/strong> organizer walks students from gravity to two bulges to two daily tides \u2014 no diagram given, so the reasoning is theirs.<\/figcaption><\/figure>\n

Featured resource<\/p>

How the Moon Makes Tides \u00b7 Graphic Organizer<\/h3>

A five-step cause-and-effect organizer that builds the whole tides model: the fact that never changes, the cause, the two bulges, the daily result, and why tides come later each day. Deliberately image-free so students do the thinking. Answer key included.<\/p>Get this organizer<\/a><\/div><\/div>\n\n

The sequence<\/span>How the whole unit fits together<\/h2>\n

Put together, these pieces make a tight teach-practice-assess arc. Here is the order that works:<\/p>\n