# Water in the 21st Century

## Water Will, Water Way

Your feedback is important to us!

After viewing our curriculum units, please take a few minutes to help us understand how the units, which were created by public school teachers, may be useful to others.

## Lesson Plan 3

Objectives:

____ Students will learn how the seas became salty.

____ Students will learn what percent of our sea, (Long Island Sound) is salty.

Unit Proceeds for one to two weeks

Materials:

2-liter soda bottles (clear or green)

sea water

window sill

Sun

large pans or bowls (to hold 4 liters of water)

Procedure/Activities/Presentation:

Why is the sea salty? Explain that the question has probably been asked as long as there have been seas (except that in the beginning, the seas were not salty). The chemical content of the heated and risen waters in the water cycle falling to earth again and again, encountering the atmospheric chemicals, and the pounding shore water running over the rocks and soils, multiplied by time, have made the seas salty! A better question for my fourth, fifth, and sixth grade students, is the one above.

In order to do this, students are grouped in fours. Each group has two 2-liter soda bottles, which they will fill with sea water; a balance, pencil, and paper. Each group should choose a recorder, weigher, calibrator, pourer etc.

Students will calibrate the balances and carefully weigh the two full soda bottles, empty pans and then the empty soda bottles after the sea water has been poured into the empty pans. Weigh the filled pans. Place the pans on the window sill so that the water will evaporate. If the weather is warm, the water will evaporate fairly quickly. If this is done without sunshine, a burner can be used to speed the process. Only the water will evaporate, leaving the salt behind. Depending on the rate of evaporation, the experiment could take up to two weeks.

Students will record all of the weights on a chart. When the salted pans are weighed, students will apply the formula, “A” equals length (l) times width (w) times depth (d) times (4). l = 110 mi; w = 21 mi; d = 60 - 300 ft. The average depth is 65 feet.

Assignments/Evaluations:

Students will use their numbers; convert the percent to a fraction and then to a decimal. These numbers can be graphed, in mathematics (curriculum tie-in). All of the groups’ numbers will then be placed on one chart. The assignment for all will be to find the Range, Mean, Median, and Mode of all the numbers on the chart.

Vocabulary List

balances

pencils

paper

burner

Range

Mean

Median

Mode

percent