Take out notebook, folder, pencil box and agenda. Walk-in Take out notebook, folder, pencil box and agenda. Copy this week’s agenda.

What Are Oceans Made Up Of?

Earth’s Waters B in each group, please get textbooks for your group. Read pages 75-77. Answer the questions on your small sheet, in complete sentences. Work check coming up!

Explain how scientists believe the Earth came to be covered in water. The earth formed 4.5 billion years ago as a ball of molten rock. As it cooled, lighter materials floated toward the surface. Water vapor cooled near the surface and by 4 billion years, cooled enough to condense to form liquid water that became the oceans.

Most of the ocean’s salt is sodium chloride. What is SALINITY? Salinity refers to the measure of the amount of dissolved salt contained in water. Most of the ocean’s salt is sodium chloride.

How do salts get into the oceans? The substances in salt (elements) are found in rocks and minerals. Rain and rivers wash some of these into the sea. They also enter the oceans when underwater volcanoes erupt.

Explain how salt content affects the density of water. The higher the water’s salt content (salinity), the greater its density. The more dense water is, the more easily things can float in it.

Why are some areas on Earth lower in salinity? Some areas on Earth are lower in salinity where the ocean is diluted by fresh water, like where rivers empty into the ocean, or where a lot of rain falls.

Density Tube Watch the video clip of a saltwater density experiment!