Modified Seawater

OBJECTIVE: The student shall demonstrate their ability to make careful observations by studying fertilization in the modified seawaters.

PURPOSE: This is a simple lesson to help students start thinking about "what if"s and "why"s.

SET: Our oceans have changed over billions of years to the current composition. As minerals are washed down from mountains, the seas have been getting more and more concentrated. Life has evolved right along side it. Are all of the components important? Can we leave some out and still get normal development? What about us? Are any of these components important to humans?


MODEL: Show the mineral composition of seawater and blood. Demonstrate how to change the solution the eggs are in.

STRUCTURED PRACTICE: Ask questions to see if students can catch the differences in seawater and blood. You could make some of each up and have them taste [seawater much saltier].

GUIDED PRACTICE: Watch students perform the experiments.

CLOSURE: Was magnesium needed? So why do you think it is there? Where did it come from? How come we don't have it in our systems?

INDEPENDENT PRACTICE: Have students propose [and] carry out further experiments in this line.