Hydrosphere: Water Distribution on Earth
Objective
Big Idea
Lesson Overview
Inquiry Based Instructional Model
To intertwine scientific knowledge and practices and to empower students to learn through exploration, it is essential for scientific inquiry to be embedded in science education. While there are many types of inquiry-based models, one model that I've grown to appreciate and use is called the FERA Learning Cycle, developed by the National Science Resources Center (NSRC):
1. Focus
2. Explore
3. Reflect
4. Apply
A framework for implementation can be found here.
I absolutely love how the Center for Inquiry Science at the Institute for Systems Biology explains that this is "not a locked-step method" but "rather a cyclical process," meaning that some lessons may start off at the focus phase while others may begin at the explore phase.
Finally, an amazing article found at Edudemic.com, How Inquiry-Based Learning Works with STEM, very clearly outlines how inquiry based learning "paves the way for effective learning in science" and supports College and Career Readiness, particularly in the area of STEM career choices.
Unit Explanation
In this unit, students will study each of Earth's major systems: biosphere, geosphere, hydrosphere, and atmosphere. In addition, students will investigate how these systems interact in multiple ways to affect Earth's materials and processes by conducting research, constructing graphs, creating models, carrying out scientific investigations, and analyzing real-world applications.
Summary of Lesson
Today, I open the lesson by showing a video on Earth's water. Students then explore the distribution of water on Earth by completing an investigation. At the end of the lesson, students reflect and apply their new understanding of the distribution of water by creating and analyzing a circle graph.
Next Generation Science Standards
This lesson will support the following NGSS Standard(s):'
5-ESS2-2. Describe and graph the amounts and percentages of water and fresh water in various reservoirs to provide evidence about the distribution of water on Earth.
Scientific & Engineering Practices
For this lesson, students are engaged in Science & Engineering Practice:
Science & Engineering Practice 4: Analyzing and Interpreting Data
Students construct a circle graph to analyze the distribution of water on Earth.
To relate ideas across disciplinary content, during this lesson I focus on the following Crosscutting Concept:
Crosscutting Concept 3: Scale, Proportion, and Quantity
Students use "standard units to measure physical quantities such as volume" in order to represent the amounts of salt and fresh water on Earth.
Disciplinary Core Ideas
In addition, this lesson also aligns with the following Disciplinary Core Ideas:
ESS2.C: The Roles of Water in Earth’s Surface Processes
Nearly all of Earth’s available water is in the ocean. Most fresh water is in glaciers or underground; only a tiny fraction is in streams, lakes, wetlands, and the atmosphere. (5-ESS2-2)
Choosing Science Teams
With science, it is often difficult to find a balance between providing students with as many hands-on experiences as possible, having plenty of science materials, and offering students a collaborative setting to solve problems. Any time groups have four or more students, the opportunities for individual students to speak and take part in the exploration process decreases. With groups of two, I often struggle to find enough science materials to go around. So this year, I chose to place students in teams of two or three! Picking science teams is always easy as I already have students placed in desk groups based upon behavior, abilities, and communication skills. Each desk group has about six kids, so I simply divide this larger group in half or thirds.
Gathering Supplies & Assigning Roles
To encourage a smooth running classroom, I ask students to decide who is a 1, 2, or 3 in their groups of three students (without talking). In no time, each student has a number in the air. I'll then ask the "threes" to get certain supplies, "ones" to grab their computers, and "twos" to hand out papers (or whatever is needed for the lesson). This management strategy has proven to be effective when cleaning up and returning supplies as well!
Focus
Lesson Introduction & Goal
I introduce today's learning goal: I can make a graph to show the distribution of water on Earth and write about my observations. I ask students: What does the distribution of water mean? We decide that this phrase means "how water is spread out on Earth."
Engage
I want to inspire interest in today's lesson and capitalize on student curiosity, so I show the following introductory video. This is a high-interest video that addresses the breakdown of water. To ensure active listening, I pause every 30 seconds or so and ask students to turn and and talk about their thoughts. Students make comments such as, "I can't believe that only 3% of the water on Earth is fresh water."
Now that you've watched a video about the water on Earth, I'd like you to have the opportunity to investigate this topic and experience it first hand.... so today, you'll be completing a demonstration that will help you visualize how water is distributed.
Explore
To help student truly understand how water is distributed on Earth, I set up a simple investigation for each of my ten teams of three students to complete. The goal is for students to be able to visualize how much water on Earth is salt water and how much is fresh water. After completing this investigation/demonstration, students will end up with the following Investigation Results:
- 970 mL of water in a bottle (representing all the salt water on Earth)
- 1 drop of water in a cup (representing all the fresh water on Earth in water vapor form)
- 9 mL of water in another cup (representing all the fresh water on Earth in liquid form)
- 21 mL of water in a final cup (representing all the fresh water on Earth in frozen form)
Teacher Note: The above measurements add up to 1000 mL (1 liter) of water, representing ALL the water on Earth.
Preparation
Prior to this lesson, I set out the following materials:
- 10 One-Liter Bottles of Water (filled, one for each group)
- 10 Tubs of Materials (one for each group)
- 4 Cups, 1 Pipette, 1 Graduated Cyclinder, & Paper Towel (materials in each tub)
- 5 Tape Dispensers (1 dispenser shared between two groups)
How Many Milliliters are in the Bottle?
First, I want to demonstrate the number of milliliters in a one liter bottle as it seems like a 1-liter graduated cylinder is bigger than the 1-liter bottle: Empty Liter Bottle & Graduated Cylinder.
I hold up an empty one-liter bottle and a 1000mL/1 Liter graduated cylinder, filled with water to the 1000 mL mark. I am careful to not tell the students how big the liter bottle actually is!
Turn and talk: How many mL of water are in this one-liter graduated cylinder? Students respond, "1000 mL are in a Liter!"
Turn and talk: How many mL do you think are in this bottle? Student responses vary: 800 mL, 500 mL, 1000 mL.
I then pour all 1000 mL of water in the graduated cylinder into the 1-liter bottle. Many students are astonished and share out loud, "It's 1000 mL!" and "That's 1 Liter!"
I explain: Today, you will be investigating how water is distributed (or spread out) on Earth. Referring to the 1-liter bottle filled with water, I continue: This bottle of water represents ALL the water on Earth. Turn and talk: How much of this bottle of water do you think represents all the salt water on Earth? Some students begin guessing while others recall from the video: 97% of the water on Earth is salt water.
As soon as students have all the supplies needed for the investigation, I ask the teams to begin reading and following the directions on the The Distribution of Water on Earth Investigation. I purposefully encourage the students to independently make sense of the directions as this is an important skill to learn at the 5th grade level.
Monitoring Student Understanding
Once students begin working, I conference with every group possible. My goal is to support students by asking guiding questions (listed below). I also want to encourage students to engage in Science & Engineering Practice 7: Engaging in Argument from Evidence.
- What patterns have you noticed?
- Why do you suppose ____?
- What have you found so far?
- Has your thinking changed?
- What evidence do you have?
- How did you decide _____?
- What conclusion can you draw about ____?
Student Conferences
While conferencing with this group, Students Distributing Water, I want to make sure that students are truly thinking about what each cup/bottle of water represents.
Here, Students Explaining Their Findings, the group not only describe what they have found by completing this investigation, but they also begin explaining their thoughts as well. This is an important part of making science meaningful to students.
After cleaning up, students were ready to apply their understanding of the water distribution on Earth by creating a circle graph.
Reflect & Apply
Sharing Findings
Now that students have built meaning and understanding by observing, questioning, and exploring, it is important to provide students with the opportunity to share their findings. For this reason, I pass out a Circle Graph & Observations sheet to each student.
Teacher Modeling
To complete today's circle graph, I will provide quite a bit of teacher modeling. This way, students can successfully create another circle graph on their own tomorrow!
I begin by projecting and taking notes (one at a time) on my Teacher Model while asking for student feedback. This circle graph represents all the water on Earth. We want to color in the amount of water that is salt water and the amount of water that is fresh water. What do you think the title of this circle graph could be? As a class, we come up with, "Distribution of Earth's Water."
Salt Water Notes
I take note and explain: It's important to know that 97% (970 mL out of 1000 mL) of all water on Earth is saline (salt) water. In order to make this water suitable for humans to drink, the water has to go through a desalinating process to take out the the salt. This process is very expensive.
Fresh Water Notes
It's also important to know that 3% (30 mL out of 1000 mL) of all the water on Earth is fresh water. This water is suitable for humans to drink. However, not all fresh water is readily available for consumption. The fresh water on Earth is in 1) solid form, 2) liquid form, and 3) gas form. Who can tell me an example of fresh water in solid form? (ice caps & glaciers) Liquid form? (lakes and rivers) Gas form? (water vapor)
Understanding the Circle Graph
When we look this circle graph, I want you to think about the whole circle representing 100% of the water on Earth. Turn and talk: If the whole circle is 100%, what do you think each of these sections represent? At first, I hear some students guessing 5%, 10%, or 20%. Then, they begin to analyze the graph closer and realize there are ten sections. With time, students decide that each section represents 10%, so we label each section 10%.
Coloring Graphs
Now, I know students are ready to work together with their elbow patterns to color their graphs to show 97% of the Earth's water is salt water and 3% is fresh water. To get students started, I ask them to turn and talk: If each section of this graph is equal to 10%, how would you find 3% to represent the amount of water on Earth that is fresh water? I rotate around the room to ensure students understand before coloring their graphs in with marker: Student Finding 3%.
Making Observations
As students finish coloring their graphs, I ask students to begin making observations below. To get students started, I provide two prompts, "I noticed..." and "This makes me wonder..."
I also invite students to share their thinking out loud. Although this student addresses a pretty extreme scenario (human extinction), I appreciate that he's really thinking about the data: Student Sharing Observations.
Student Examples
Here are a couple examples of student observations during this time:
