Salty Sea

The Salty Sea

Goals:

1. To understand why the sea tastes salty and understands the difference between saltwater and freshwater.
2. Effectively perform the saltwater and freshwater experiment.

Resources:

Bingham, C. & Hansen, P. (1994). "Why is the sea salty?" http://covis.atmos.uiuc.edu/geosciences/students/ocean/ocean.html

Materials:

For teacher: two bottles, sand, 2 buckets of water: freshwater and saltwater.

For students: black paper, saltwater, salt, warm water, white paper, and food coloring.

Time:

90 minutes

Teacher Preparation:

1. Motivation and preparation for students: The teacher will perform the experiment to prepare the students.
2. The teacher will fill each of the bottles with sand. The teacher will take the two buckets and fill them with
water; one with the saltwater and one with the freshwater. Then take each of the bottles and place them
simultaneously into the buckets of water; one bottle in the freshwater bucket and one in the saltwater bucket.
Explain how the bottle in saltwater floats higher since saltwater has better buoyancy than freshwater.

Discussion and Research:

Students write prediction to why he/she thinks the bottle floats higher in saltwater than freshwater
Teacher: Why is saltwater more buoyant? Density
Explain how density is result of salinity, temperature, and depth. Salinity varies throughout oceans of the world.

Procedure:

1. Give the student a piece of black paper, and then place a drop of saltwater on each student’s paper.
2. Have students let the water evaporate and eventually notice the salt left behind, hence, the students learn why ocean water tastes salty.
3. Next, give each student a piece of white paper. Give each student a mixture of warm water, salt, and food coloring.
4. Have the students use the mixture to paint pictures onto the white paper. When the painting is dry, the students will notice that just the colored salt remains.

Assessment:

1. Participation, collection of predictions, and discussion on why a bottle in salt water floats higher than a bottle in freshwater.

2. Completion of art projects pertaining to saltwater evaporation.

3. Criteria for success = completion of art project and turned in to the teacher, and also collection of thoughtfully planned-out predictions.

Curricular Strands and Major Concepts:

1. Art- art skills in completing experiments to discover salt traces left from evaporation.
2. Science- determining and discovering differences between saltwater and freshwater.

Possible Extensions:

Predicting salt content from evaporation of different amounts of saltwater.
Discuss the uses of freshwater as opposed to saltwater on the slave ships. How did the slaves hold freshwater on the ships back then. What would the slaves do if they ran into a shortage of freshwater out on an ocean of saltwater.