An Ocean Unit Study for Elementary School, Week by Week

It grabs attention on day one and leaves the unit nowhere to climb. Everything after the anglerfish feels like a step down.

Start with water itself, finish in the deep. Children who have spent four weeks on salt, food webs and layers understand why the deep sea is dark, cold and crushing, which beats being told it is.

They are one system. Rivers carry the salt to the sea, and the sea's water comes back as rain. Estuaries, where the two meet, are some of the most productive habitats there are.

Teaching them in separate units hides the most interesting water on the map.

About 2.5 percent of all Earth's water is fresh, and over 68 percent of that fresh water is ice. Put both on one chart without labels and a child will conclude that most of the planet's water is frozen.

Draw two separate graphs: all water first, then a second bar for fresh water only. It is the exact confusion the week-one lesson is meant to clear up.

Most posters give the sunlight zone, twilight zone and deep sea the same height on the page. At true scale, the sunlight zone is a thin skin, about one-twentieth of the average depth.

The paper strip in the hallway fixes this, and it is the moment in the unit that children remember.

The demonstration layer is roughly three times saltier than seawater, on purpose, so the line is sharp and slow to mix.

A real halocline is weaker and is stirred all the time by wind, tides and river flow. Say so while the cup is on the table. That is a better fact than a neat one.

A unit study teaches several subjects through one topic over a few weeks, instead of separate lessons for each subject.

Here the topic is the ocean. Children read, graph, experiment and write about the same water for five weeks, and reading, maths and science all come out of it.

Five weeks at three sessions a week is what this one is built for, about forty-five minutes each time.

You can squeeze it into three weeks by dropping the book in week three and combining weeks one and five. Going faster than that turns it into a list of facts, and the experiments need time to be repeated.

It is written for Grades 2 to 5, roughly ages seven to ten, which matches the books and teacher notes it uses.

Kindergarten and Grade 1 can do the egg float, the salt-line cup, the string food web and the hallway depth strip. Leave out the graphing, and let them draw in the log rather than write.

Week one uses the Real Scientists Ask Questions poster. Weeks two to four use the teacher notes and reading quiz for Books 1, 2 and 3, plus the Mosquito Patrol poster.

Week five uses the reading badges. There is no deep-sea worksheet, so the class makes the depth strip itself. Everything downloads free from the Educators page.

Weeks one and five need no book at all. Weeks two to four are built around Books 1, 2 and 3, because the teacher notes follow them chapter by chapter.

The notes never give away the story, so you can plan from them first and borrow the books from a library.

It gives you an opportunity to address six performance expectations, listed on this page in their official wording. The week-one graph is very close to 5-ESS2-2 as written.

We say opportunity on purpose. A unit does not teach a standard by itself, and several large states use their own framework.

About 2.5 percent, according to the U.S. Geological Survey. The oceans hold about 96.5 percent, and the rest is salty groundwater and saline lakes.

Of the fresh water, over 68 percent is locked in ice and glaciers and about 30 percent is underground. Lakes and rivers are a very small slice.

NOAA puts the average depth at about 3,682 meters, or 12,080 feet. The deepest known point, Challenger Deep in the Mariana Trench, is about 10,935 meters, or 35,876 feet.

Sunlight is strong enough for photosynthesis only in the top 200 meters or so, which is a thin skin on a very deep ocean.