Why Taiwan has earthquakes
Explain why earthquakes follow plate boundaries, using this month's real earthquakes.
Lessons
25 short lessons, about five minutes each. 15 play right here; every lesson has a full page you can read and share.
Restless Earth
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Magnitude: one step is a big step
Understand that magnitude is logarithmic, and tell magnitude apart from the shaking felt at a place.
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Ridges, trenches and faults
Name the three main kinds of plate boundary and what each one builds.
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Volcanoes and the Ring of Fire
Explain why most volcanoes sit on plate boundaries and how hot spots make the exceptions.
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Why some earthquakes make a tsunami
Explain how a tsunami starts, how it travels and what to do near the coast.
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How deep do earthquakes go?
Read earthquake depths and use them to trace a plate sinking into the mantle.
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Earthquake early warning
Explain P- and S-waves and how an early-warning system wins a few seconds.
Air in motion
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The global wind machine
Explain the pattern of the trade winds, the doldrums and the westerlies from uneven heating and the Earth's spin.
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The monsoon year
Explain why the wind over Taiwan and India reverses between winter and summer.
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How a typhoon forms
Name the conditions a typhoon needs and explain where its energy comes from.
Reading the weather
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Why mountains are colder
Use two cities' typical years to show how temperature falls with height.
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The daily swing
Use the forecast timeline to see why some places swing more than others between day and night.
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Highs, lows and the spin
Read isobars, find highs and lows, and link them to wind direction, wind speed and weather.
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How strong is that wind?
Read wind speed and the Beaufort scale, and explain why wind is strongest over open sea.
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How radar sees rain
Explain how weather radar measures rain, how it differs from a forecast, and why mountains make wet and dry sides.
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Reading a typhoon forecast
Read a typhoon track and forecast cone, and explain why slow, rainy typhoons are dangerous.
Ocean
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The warm sea and its currents
Read a sea temperature map, find the warm pool, upwelling and warm currents, and explain why the sea changes temperature slowly.
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El Niño and La Niña
Describe what changes in the Pacific during El Niño and La Niña, and read NOAA's index.
Climate
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Climate zones
Read a Köppen climate map and link the zones to latitude, wind belts and the distribution of land.
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The sea effect
Use two cities' typical years to show how the sea narrows the gap between summer and winter.
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Seasons: tilt, not distance
Explain the seasons with the tilt of the Earth's axis, using day length and the height of the noon Sun.
Space around Earth
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Why the ISS track moves west
Explain what keeps a satellite in orbit and why its ground track shifts with each orbit.
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How your phone knows where it is
Explain how satellite navigation turns signal travel times into a position.
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Your compass and the wandering pole
Explain why a compass does not point to true north and where the Earth's magnetic field comes from.
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Why the sky lights up: aurora
Explain where aurorae appear and why, and read a live aurora forecast and the Kp index.