Water scooped from the ocean tastes salty, but water from most lakes and rivers does not. What word names how much salt is dissolved in water?

Along a beach, the sea slowly rises and then falls again in a regular daily pattern. This rise and fall is called a tide. What causes tides?

As a wave passes through open water, a floating cork bobs up and down but stays in about the same spot instead of traveling toward shore. What does this show about how a wave moves water?

True or False: Along most ocean coastlines, the water rises to high tide and falls to low tide about twice every day.

A message in a bottle is dropped in the ocean near Florida. Months later, it washes ashore in Europe, thousands of miles away. Which kind of ocean water movement most likely carried it that far?

Wind helps push ocean currents along. What else helps keep large ocean currents moving?

Walking out from a beach, a class finds that the water stays shallow for a long way before the bottom drops off. What is this shallow part of the ocean floor near land called?

Scientists study several features of the ocean floor. Which feature is found at the deepest places in the ocean?

A research ship leaves the shore and sails straight out to sea, measuring the depth of the water as it goes. What pattern will the measurements most likely show?

A small submarine dives from just below the surface down toward the deep ocean floor. What happens to the pressure of the water pushing on the submarine as it goes deeper?

Past the edge of the continental shelf, the ocean floor suddenly drops away and slopes steeply down toward the deep sea. What is this steep, sloping part of the ocean floor called?

What is an ocean?

True or False: Oceans cover less than half of Earth's surface.

What makes ocean water different from most lake or river water?

Far from any coast, the deep ocean floor spreads out as a wide, flat area covered with a thick layer of soft mud and sediment. What is this flat part of the deep ocean floor called?

In the middle of some ocean basins, an underwater mountain chain rises from the ocean floor where two pieces of Earth's crust are slowly spreading apart. What is this underwater mountain chain called?

True or False: In most parts of the ocean, the water gets colder as you go deeper below the surface.

Scientists find an underwater mountain rising from the ocean floor, but its peak stays far below the water's surface. What is this kind of underwater mountain called?

Starting at the beach and moving straight out toward the open ocean, which lists these ocean-floor features in the order you would cross them?

Which statement correctly compares a wave and a current?

Twice a day, the ocean water along a dock rises and falls, but a nearby buoy floating offshore does not steadily drift toward the shore during this rise and fall. Which ocean movement is being described?

An egg sinks in a glass of fresh water but floats in a glassful of ocean water. What property of ocean water explains why the egg floats more easily?

Some underwater volcanoes build tall mountains that rise from the ocean floor but do not reach the surface. What are these mountains called?

What is an estuary?

Water in an estuary is often called brackish because it is what?

In the middle of the Atlantic Ocean, surface currents flow together to form one large, slow-moving circular pattern that covers much of the ocean basin. What is this large circular pattern of currents called?

What causes most ocean surface waves?

The Sun is much bigger than the Moon, but the Moon has a stronger effect on ocean tides. Why does the Moon pull on the tides more than the Sun does?

True or False: At low tide, more of the beach and the rocks along the shore are uncovered than at high tide.

What are ocean currents?

How can ocean currents affect climate near a coast?

When ocean water evaporates, what is left behind?

True or False: Ocean water can evaporate and later fall as rain in the water cycle.

What is coastal erosion?

What can waves deposit on a beach?

A ship's sonar shows the ocean floor plunging into a long, narrow, very deep valley, far deeper than the surrounding seafloor. Which ocean-floor feature is the sonar most likely detecting?

During a full moon, a beach shows an especially big difference between its high tide and its low tide. What causes tides to be extra high and extra low around the full moon and new moon?

True or False: When the tide goes out, all of the seawater drains off the rocky shore, leaving no pools of water behind.

About how much time usually passes between a high tide and the next low tide at the same beach?

Because tides follow a predictable daily pattern, people who fish or launch boats from the shore often check a printed or online tide chart before heading out. What is this chart most useful for showing them?