ESL Lesson | C1 | Earth science: where did Earth’s water come from?

Summary

This C1 ESL lesson explores the fascinating question of where Earth's vast water supply originated. Students will engage with a captivating video to enhance listening comprehension, expand their scientific vocabulary, and practice advanced conditional sentences.

The lesson plan guides advanced learners through a journey from initial planetary formation to current theories involving comets and asteroids. Activities include a warm-up discussion on water's importance, a listening gap-fill exercise, vocabulary matching, grammar practice focused on Type 3 and mixed conditionals, and a speaking task to apply new knowledge and language.

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Activities

A warm-up discussion where students consider the significance of water and initial hypotheses about its origin.
Video comprehension questions and a gap-fill exercise based on a TED-Ed video exploring different scientific theories on Earth's water source.
A vocabulary matching task introducing key scientific terms and general advanced vocabulary from the video, such as "take for granted," "outgassing," and "eons."
A grammar exercise focusing on Type 3 conditional and mixed conditionals, allowing students to discuss hypothetical past events and their present or past results related to Earth's formation.
Practice with common English water-related idioms like "hold water," "a drop in the ocean," and "in hot water."
An exercise to use the new vocabulary in context, reinforcing understanding.
A matching activity to connect theories about Earth's water origin with their descriptions.
A speaking practice session where students discuss and debate the theories, applying new vocabulary, idioms, and conditional structures.

00:06 It has no taste, color, or smell, and we often look right through it.

00:12 It covers over 70% of the Earth,

00:15 cycling from the oceans and rivers to the clouds and back again.

00:20 It even makes up about 60% of our bodies.

00:24 With all this water around and inside us,

00:27 it's easy to take its presence for granted.

00:30 But in the rest of the solar system, liquid water is almost impossible to find.

00:36 So how did our planet end up with so much of this substance

00:40 and where did it come from?

00:42 As you probably know,

00:43 a water molecule consists of two basic parts.

00:47 Hydrogen, the simplest of all elements,

00:49 has been around since close to the beginning of our universe.

00:53 Oxygen entered the scene several hundred million years later

00:57 after stars began to form.

00:59 The massive pressure at the center of these fiery infernos was so great

01:05 that hydrogen atoms fused together to form helium.

01:09 Helium, in turn, fused to form heavier elements,

01:12 like beryllium, carbon, and oxygen in a process known as nucleosynthesis.

01:20 When stars eventually collapsed and exploded into supernovas,

01:25 these new elements were spread across the universe

01:29 and combined into new compounds, like the now familiar H2O.

01:34 These water molecules were present in the dusty cloud

01:37 that formed our solar system

01:39 and more collided with our planet after its formation.

01:43 But there's a big question that we don't have the answer to:

01:46 how much water arrived on Earth, and when?

01:50 If, as one theory goes,

01:52 relatively small amounts of water were present on Earth when the rock formed,

01:57 the high temperatures and lack of any surrounding atmosphere

02:00 would have caused it to evaporate back into space.

02:03 Water would have been unable to remain on the planet

02:06 until hundreds of millions of years later

02:08 when our first atmosphere formed through a process called outgassing.

02:13 This occurred when molten rock in the Earth's core

02:16 released volcanic gasses to the surface,

02:18 creating a layer that could then trap escaping water.

02:21 So how then did water get back to the planet?

02:24 Scientists have long suspected

02:26 that much of it was brought by ice-bearing comets,

02:29 or more likely asteroids that bombarded the Earth over millions of years.

02:34 Recent research has challenged this theory.

02:37 In examining carbonaceous chondrite meterorites

02:40 that formed shorty after the birth of our solar system,

02:43 scientists have found that not only did they contain water,

02:47 but their mineral chemical composition matched rocks on Earth

02:51 and samples from an asteroid that formed at the same time as our planet.

02:56 This suggests that the Earth may have accumulated

02:58 a substantial amount of water early on that was able to stay put,

03:02 despite the lack of an atmosphere,

03:04 though asteroids may have brought more over the eons.

03:08 If this turns out to be true,

03:09 life may have formed much earlier than previously thought.

03:13 So we do not yet definitively know whether the water on Earth

03:17 came from its initial formation,

03:19 later impacts,

03:20 or some combination of the two.

03:23 Regardless, the water that runs from our showers, drinking fountains, and faucets

03:28 is something that didn’t just come from a nearby lake or river,

03:32 but first underwent a cosmic and chaotic journey to get here.

Vocabulary focus

The vocabulary section introduces and reinforces advanced terms related to astronomy, geology, and general scientific discourse. Key terms include "take for granted," "consist of," "outgassing," "bombard," "accumulate," "definitively," "eons," and "chaotic." Students will practice these terms through matching definitions and using them in context.

Grammar focus

This lesson concentrates on Third Conditional and Mixed Conditionals (often Type 3 + Type 2). Students will practice constructing sentences to discuss hypothetical past situations and their hypothetical past or present results, such as "If Earth hadn't had a dense atmosphere early on, much of its initial water would have evaporated." and "If comets and asteroids hadn't delivered water, our planet would be much drier today." This reinforces advanced conditional structures in a scientific context.

Earth science: where did Earth’s water come from?

Summary

Activities

Vocabulary focus

Grammar focus

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