The Distribution of Water on Earth
Lesson 2 of 5
Objective: SWBAT recognize, represent, and describe the distribution of water on Earth.
5e Lesson Plan Model
Many of my science lessons are based upon and taught using the 5E lesson plan model: Engage, Explore, Explain, Elaborate, and Evaluate. This lesson plan model allows me to incorporate a variety of learning opportunities and strategies for students. With multiple learning experiences, students can gain new ideas, demonstrate thinking, draw conclusions, develop critical thinking skills, and interact with peers through discussions and hands-on activities. With each stage in this lesson model, I select strategies that will serve students best for the concepts and content being delivered to them. These strategies were selected for this lesson to facilitate peer discussions, participation in a group activity, reflective learning practices, and accountability for learning.
The Water on Earth Unit focuses on the interaction of the hydrosphere with other Earth systems including the geosphere, biosphere, and atmosphere. Through models, investigations, research, graphing, and multimedia, students learn that the amount of water on Earth never changes and the amount available for human consumption is small. They identify and calculate the distribution of water sources on Earth, distinguish the properties of various forms of water, and recognize the cycling of water in and out of the atmosphere.
This lesson, The Distribution of Water on Earth, begins with students brainstorming ways people use water and generating a top ten list. We compile a class list of their ideas and think of sources of water from which people might get water. I use a powerpoint slide to briefly describe these sources. Then students take part in 2 investigations to determine how much water is available for human consumption. First they create a model to compare the amounts of ocean water and freshwater on Earth. Then, they create models to illustrate the different sources within a freshwater system. They organize their data into a table which is then used to create a circle graph to visually depict the information. The lesson wraps up with students writing an analysis of what they notice about water distribution on Earth.
Next Generation Science Standards
This lesson will address and support future lessons on 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.
Students are engaged in the following scientific and engineering practices:
2.) Developing and Using Models- Students create several models to describe the distribution of water on Earth.
4.) Analyzing and Interpreting Data- Students create a data table and circle graph to represent the relationships between the distribution of water on Earth. They use computation to calculate the percentage of a particular water source on Earth.
5.) Using Mathematics and Computational Thinking- Students calculate the distribution of water on Earth by using an equation to find the amount in percent. They use this percentage to create a graph illustrating the differences.
The Distribution of Water on Earth lesson will correlate to other interdisciplinary areas. These Crosscutting Concepts include:
3. Scale, proportion, and quantity- Students conduct an investigation by using relative scales to describe the distribution of water on Earth. They use data from their investigation to provide evidence that there is a limited amount of freshwater on Earth.
Disciplinary Core Ideas within this lesson include:
ESS2.C: The Roles of Water in Earth’s Surface Processes
Classroom Management Methods
Importance of Modeling to Develop Student
Responsibility, Accountability, and Independence
Depending upon the time of year, this lesson is taught, teachers should consider modeling how groups should work together; establish group norms for activities, class discussions, and partner talks. In addition, it is important to model think aloud strategies. This sets up students to be more expressive and develop thinking skills during an activity. The first half of the year, I model what group work and/or talks “look like and sound like.” I intervene the moment students are off task with reminders and redirection. By the second and last half of the year, I am able to ask students, “Who can give of three reminders for group activities to be successful?” Who can tell us two reminders for partner talks?” Students take responsibility for becoming successful learners. Again before teaching this lesson, consider the time of year, it may be necessary to do a lot of front loading to get students to eventually become more independent and transition through the lessons in a timely manner.
- EXPLORE TEAMS (Pre-Set)
For time management purposes, I use “lab rats ” where each student has a number on the back of his or her chair, 1,2,3,4 (students sit in groups of 4)and displayed on the board. For each activity I use lab rats, I switch up the roles randomly so students are experiencing different task responsibilities which include: Director, Materials Manager, Reporter, and Technician. It makes for smooth transitions and efficiency for set up, work, and clean-up.
Activating Prior Knowledge
I introduce today's lesson by bringing student's attention the board where the question "How do people use water?" is displayed. I read this question out loud and explain that they are are brainstorming 10 ways they use water in their lives. I hand out a "Top Ten" brainstorming sheet and tell them to begin.
I selected the Top Ten to activate students' prior knowledge and engage them in thinking about water's role in their personal lives. I want them to recognize the many ways they use and depend on water.
When I notice most students are ready, I reconvene the class as a whole and say: "Looking at your list, do you think we need water to survive?" I ask them to give me a thumbs up for yes, thumbs down for no, and thumb in the middle for not sure. I continue on, "Let's see all the ways we use water in our lives by doing a word splash. Each group shares one item from their list to write on the board. Each group sends one member to the board one at a time. After one member from a group shares, they pass the marker to another group member, this process is repeated until each group member has written an idea on the board. By the end of the shares, a class list is created on the board for the whole class to observe.
After analyzing the splash of ideas, I ask them, "Where do we get the water we need?" We brainstorm natural sources of water on Earth and create a table on the board. I ask students to recreate this table in their interactive notebook.
Sources of Water
Form-Solid, Liquid, Gas
3.) Surface water
4.) Glaciers & Ice Caps
I project a powerpoint briefly describing each source of water. I point out that groundwater and surface water are primary sources of water for people to drink.
As I go through each one, I have students write down key facts about each water source. Together we identify what form the water is in. I make a point to identify its phase so students recognize that water can be in different forms.
Preparing to Investigate
After creating our table of water sources on Earth, I tell students we are creating a model to look at how water is distributed across these sources. Using our lab rats roles, I hand out a task card and ask students to set up their interactive notebook. Once our notebooks are set up and lab rats' material manager retrieves the materials. I review the directions.
Investigation 1: Ocean Water vs Freshwater
First students create a model to represent the ocean water and fresh water. I do this so students initially see the difference between the amount of ocean water and fresh water on Earth. They fill a 1000ml beaker with 970 ml of water and add two drops of blue food coloring to represent the ocean. Next, they pour 30ml of vegetable oil into the beaker, this represents the freshwater. I use vegetable oil because it floats and gives the students a distinct visual of freshwater in comparison with the blue ocean water.
When this model is set up, I reconvene the students to discuss their model. I explain to them the 1000 ml beaker represents 100% of water on Earth's. If 97% of the water on Earth is the ocean, what percent of the water in Earth is freshwater? They should recognize the difference between 100% and 97%. (I show them how I calculated 970 ml to equal 97%.____ml /1000=_____x100 = ____%. I leave this equation on the board as it will be used to calculate the different sources of freshwater.
I point out that while Earth is made up of a large amount of water, only 3% percent is freshwater. We discuss how this limited amount of water must support living organisms like people, animals, and plants. I explain that ocean water is unavailable for use by plants and animals that live on land because it contains salt.
Investigation 2: Water Sources that Make Up Freshwater
Now I direct students attention to the second part of the investigation on their task card and review their directions.
I start off asking: "Looking at your first model, how much of Earth's water is made up of freshwater?" This question lets them reanalyze their first model to distinguish between ocean water and freshwater. The freshwater is represented by the vegetable oil floating on top of their blue ocean water.
I continue by asking, "How much of this freshwater do you think is available for people to consume?" I take a few shares and note them on the board. Then I direct them to set up their second set of models. The model begins with 30 ml of water. This represents the freshwater, which is equivalent to the vegetable oil from the first step. From here, they take away certain amounts and set it aside to represent other water sources we identified at the start of the lesson. 25ml of that water is taken from the cylinder and poured in a container labeled glaciers and ice caps. 4.2 ml is taken and poured into a container and labeled as groundwater.
After removing these amounts, I ask: "How much water is remaining in the beaker?" Students should observe it and determine it is about .08 ml. This amount represents the amount of surface water (rivers, lakes, and reservoirs) on Earth.
We discuss how the remaining water is supposed to support all the living organisms on Earth. I explain that in people, water makes about 70% of the body; therefore, it is important to consume it. I further explain that water is such a vital resource that is important to understand how much is available, which is why we created the models. I explain that freshwater is a limited resource; therefore it is important to conserve it in our daily lives. I engage them in discussing ways to conserve water.
To make this more concrete, I show this Water On Earth Video. I selected this video because it provides a clear explanation of the amount of water on Earth and how freshwater is used. It helps students recognize the importance of conserving water.
After creating models of the waters on Earth. I explain that they are taking the measured amounts of each water source and organizing it on a data table. I hand out the table and review their task. They are taking each amount of water and calculating each one into a percentage. I review with them how to do this. (I refer back to the equation presented earlier in the lesson.) I do provide calculators as decimals and percents is taught later in the year.
Once students have created their data table, I walk them through setting up their circle graph. I place a circle graph (located underneath their data table) under the document camera and point out that the graph represents 100%; therefore, the data needs to be arranged into each portion of the graph according to its calculated percentage. We discuss the increments displayed on the graph and talk about labeling them them in a way that totals 100%. Students should come up with labeling each as 10%.
Following the circle graph set up, I have students graph their data to represent the distribution of water on Earth. When their graph is complete, I have them shade in each portion of the graph a different color so they can visually see the differences between the distributions. In addition, they create a graph key to distinguish the between them.
With a data table and circle graph complete. I instruct students to write a data based observation:
"Describe the distribution of water on Earth. Summarize how your investigation models the amount of water on Earth."
They write their analyses in their interactive notebook. I am looking for them to recognize the small amount of freshwater available on Earth for people. For this written analysis, students should summarize what they have learned about the amount and distribution of water on Earth. In addition, they explain why water conservation is important.
They work on their written analysis for the remainder of the class and finish for homework. I collect them and use as a formative assessment.