ALEX Lesson Plan

If water covers 70-75% of our planet, then why should we be concerned about water quality and conservation? This lesson helps students understand that 97% of our water is present on Earth in the form of salt water, and therefore, unavailable for helping support life on Earth. Another 2% of Earth's water is frozen, which leaves us approximately 1% in groundwater, lakes, streams, and water vapor. 

This lesson was adapted from a lesson series from 4-H SET (California).

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

20-inch inflatable globe

5-gallon container, filled with water (one per group)

Calculators (one for each student)

5 clear plastic cups (one set for each group)

1 mL plastic syringe (one for each group)

1 beaker or graduated cylinder (one for each group)

paper towels

sticky notes

National Geographic Water Video

Students should understand that standard units are used to measure and describe physical quantities such as the amounts of salt water and fresh water in various reservoirs.

Students will need to know how to measure liquids using a syringe. 

ENGAGE:

Ask the students these questions and record responses in a location that will be visible throughout the lesson:

1. What do you know about water?

2. Why is water important to life on Earth?

Have students stand in a circle and softly toss the inflatable globe to one another. Have each student remember if their thumb landed on land or water. The majority should have landed on water. 

Ask the students: Why do you think so many of us landed on water?

Students should express the idea that our Earth is covered mostly by water. 

Ask the students: What percentage of the Earth's surface is covered by water? 

Allow them to guess or predict what they think.

Tell students that 70-75% of Earth's surface is covered by water. 

EXPLORE:

Teacher: So if 70-75% of Earth is covered by water, then we should have plenty of water, right? Let's find out. 

Tell each group that the 5-gallon container represents all of the water on Earth. Have the students use their plastic syringes to remove the following amounts of water from the large container and then place those amounts into the individual cups. Each portion measured should be placed in a separate cup.

Have the groups label their cups by placing a sticky note beside each cup with the following information:

0.2 mL= fresh water as water vapor

0.9 mL= fresh water in soil

1.7 mL= fresh water in rivers, streams, lakes

118 mL (1/2 C)= fresh water in groundwater

414 mL (1 3/4 C)= fresh water in polar caps and glaciers

Ask the students:

What is left in the large container? 

What does this represent? 

Be sure that students understand that the water remaining in the large container represents salt water and that salt water cannot be consumed by plants and animals on Earth because of its salt content. 

EXPLAIN:

Have students calculate the percentage that each amount represents out of all the water on Earth. 

The total amount in the bucket was 18,927 mL before any water was removed.

The bucket now contains 18,394.7 mL  To find the percentages, students should use the calculator and divide the amount in each cup by the total amount in the bucket. 

KEY:

Water vapor=0.001%

Soil moisture=0.005%

Freshwater rivers, streams, lakes=0.009%

Groundwater=0.6%

Polar Ice Caps and Glaciers=2.2%

Oceans and other saltwater sources=97.2%

ELABORATE:

Now since students have calculated the percentages, have each student record them on one side of an index card. Have students turn and talk to a partner and discuss why they think this is significant/important. 

Show the video: Why Care About Water? (National Geographic)

EVALUATE:

As a formative assessment, students should write these percentages on one side of an index card. On the opposite side, students should explain why this is important for us to understand. 

As a formative assessment, students should write these percentages on one side of an index card. On the opposite side, students should explain why this is important for us to understand. 

Optional Extensions:

Research current issues related to water conservation and the availability of freshwater in the United States. 

Develop a list of ways to conserve water at school and present those ideas to the class and to school administrators. 

Some students may struggle with making the percentage calculations. Allow them to make comparisons between the containers of water without concentrating specifically on the percentages. 

For ELLs: provide vocabulary picture cards with photos representing terms that may not be familiar to them. (water vapor, soil, rivers, streams, lakes, groundwater, polar ice caps, glaciers, oceans)