Science · 1st Grade · Earth's Systems and Changes · Weeks 19-27

Water on Earth

Students investigate where water is found on Earth and its importance to living things.

• Common Core State Standards
• 2-ESS2-3

About This Topic

Water is the most essential natural resource on Earth, and first grade students in the US are ready to begin mapping where it exists and why it matters. Standard 2-ESS2-3 focuses on students using data to describe the variety of places water is found on Earth, the changes it can go through, and its role in living systems. Students learn that most of Earth's water is in the ocean and is saltwater, that freshwater is found in rivers, lakes, glaciers, and underground, and that living things depend on freshwater to survive.

This topic naturally sparks questions students already have: Where does tap water come from? What would happen if a drought lasted for years? Why can we not drink ocean water? Those questions make this content highly engaging for six-year-olds, and US classrooms often connect this topic to local water sources and state-level conversations about water use and conservation.

Active learning approaches work particularly well here because students can observe and test water in multiple forms. Structured investigations comparing salt water and fresh water, mapping water on a class globe, or tracking a raindrop's journey through a collaborative diagram build a multi-perspective understanding that reading a textbook page cannot replicate.

Key Questions

1. Explain where most of Earth's water is located.
2. Analyze the importance of water for plants, animals, and humans.
3. Predict what would happen if a region ran out of fresh water.

Learning Objectives

• Identify the primary locations of Earth's water, classifying them as saltwater or freshwater.
• Explain the dependence of plants, animals, and humans on freshwater for survival.
• Analyze the potential consequences for a community if its freshwater supply is depleted.
• Compare and contrast the properties of saltwater and freshwater in relation to their uses.

Before You Start

Basic Needs of Living Things

Why: Students need to understand that all living things require certain things to survive, including water, to grasp the importance of freshwater.

Identifying Living and Nonliving Things

Why: This foundational skill helps students categorize organisms that depend on water, distinguishing them from nonliving elements.

Key Vocabulary

saltwater	Water that contains a high concentration of dissolved salts, primarily found in oceans.
freshwater	Water that contains very little dissolved salt, found in rivers, lakes, glaciers, and underground.
ocean	A very large expanse of sea, in particular, each of the main areas into which the sea is divided geographically. Most of Earth's water is here.
drought	A prolonged period of abnormally low rainfall, leading to a shortage of water.
conservation	The protection and careful use of natural resources, like water, to prevent them from being wasted or harmed.

Watch Out for These Misconceptions

Common Misconception

All water on Earth is drinkable.

What to Teach Instead

Many students assume water is water and all of it is safe to drink. A simple taste-safe comparison of a salty water sample and a fresh water sample, combined with a globe showing how much ocean covers the surface, makes the scarcity of fresh drinking water concrete and surprising.

Common Misconception

Water only exists above ground in rivers, lakes, and oceans.

What to Teach Instead

Students rarely consider underground water (aquifers) or water in glaciers and polar ice. Using a cross-section diagram of the ground and photographs of glaciers helps expand their mental model of where water can exist on and inside Earth.

Active Learning Ideas

Inquiry Circle: Salt Water vs. Fresh Water

Give each pair of students two cups of water, one plain and one with dissolved salt, plus a small piece of celery or a bean sprout. Students observe both over three days and record which plant part or sprout looks healthiest. The class compares results and discusses why living things on land need fresh water.

20 min·Pairs

Mapping Activity: Where Is Earth's Water?

Give students a simple outline of a world map and small blue stickers of two sizes (large for ocean, small for lakes/rivers). Students place stickers using a reference globe, then step back to observe how much of the map is ocean versus freshwater. The class calculates rough percentages together using tallies.

30 min·Small Groups

Think-Pair-Share: What If There Was No Fresh Water?

Pose the scenario: 'Imagine your town's river ran completely dry. What would change for people, plants, and animals?' Students think alone for two minutes, then discuss with a partner before the class builds a shared list of consequences on the board, organized by plants, animals, and humans.

20 min·Pairs

Real-World Connections

• City water treatment plants, like the one serving Chicago, filter and purify freshwater from sources like Lake Michigan to make it safe for drinking and daily use by millions of people.
• Farmers in arid regions, such as parts of Arizona, must carefully manage limited freshwater resources for irrigation, often using drip systems to deliver water directly to plant roots and reduce waste.
• Marine biologists study ocean ecosystems to understand the vast saltwater environments, recognizing that while they hold most of Earth's water, they are not suitable for direct human consumption or most agriculture.

Assessment Ideas

Exit Ticket

Provide students with a world map or globe. Ask them to draw and label three places where water is found on Earth, indicating whether each is saltwater or freshwater. Include one sentence explaining why one of these water sources is important for living things.

Quick Check

Hold up pictures of different living things (a plant, a fish, a child). Ask students to give a thumbs up if the living thing needs freshwater to survive and explain why. Then, ask what might happen if that freshwater disappeared.

Discussion Prompt

Pose the question: 'Imagine your town's river or lake dried up completely for a whole year. What are three things that would be very difficult or impossible to do?' Facilitate a class discussion, guiding students to connect water scarcity to daily life activities.

Frequently Asked Questions

How do you explain the water cycle to first graders?

At first grade level, focus on the observable parts: rain falls, puddles evaporate, clouds form, and rain falls again. A simple diagram with arrows and student-drawn pictures of each stage is more effective than formal vocabulary. Acting it out physically, where students 'become' droplets moving through stages, helps kinesthetic learners.

Where is most of Earth's water located, and how do I explain this to young students?

About 97% of Earth's water is in the ocean and is salty. Most of the remaining 3% is locked in ice or underground. Using a globe and pointing out how much is blue, then explaining that most of that blue water is not drinkable, makes the scarcity of fresh water tangible and memorable.

What books or resources support teaching water on Earth to first graders?

Picture books like 'The Water Princess' and 'A Cool Drink of Water' connect water availability to real communities around the world. NASA's water cycle diagrams and NOAA's water distribution charts are simple enough for classroom display and provide accurate visual data for young learners.

How can active learning approaches make water science more meaningful for first graders?

Hands-on comparisons, such as testing what plants do in salt water versus fresh water or mapping water sources on a globe, make the abstract fact that freshwater is rare feel real and important. Students who discover patterns themselves through investigation retain and apply that understanding more consistently.