Level 2: Ocean Unit

Ready for adventure, underwater explorers? For this week-long unit, we’ll begin by strengthening our understanding of what makes up this fascinating biome. Next, we’ll get an introduction to some of its residents, including sea turtles and sharks. Click here to download our weekly skills tracker, and then get ready to dive in!

Note: Occasionally we include project modifications (which can be useful for including younger siblings). We’ll mark those with the minus (-) symbol.

What you need:

Books (find at your local library or order below on Amazon):

Optional additional reading:

Supplies (use what you have, but here are links to shop if you need anything):

What to do:

We recommend doing the below lessons in this order to build on each skill your child will develop, but don’t feel that you *need* to do them in this order. Do what works for you and your child. If they love an activity, feel free to repeat! Not a winner? Skip and try the next thing. Have fun!

Phonics Guide:

New to our phonics guide? Start here. The Phonics Guide this week will highlight the /sh/ sound.

Lesson 1:

In previous units, we’ve learned about terrestrial (or land) biomes, but this week, we’re all about the marine biome! The marine biome is the largest on the planet, covering about 70% of the earth.  It includes five main oceans: the Pacific, Atlantic, Indian, Arctic, and Southern, as well as many smaller gulfs and bays. To start, let’s listen to this simple song to help your child learn and remember the five oceans. Next, let’s read Down, Down, Down: A Journey to the Bottom of the Sea (or read it here on OpenLibrary) before diving into our activities.

Activity 1: The ocean is divided up into three vertical zones. The top layer is called the euphotic zone and it is the area of the ocean where light can penetrate. The next layer is the disphotic zone. This area is too deep for lots of light to reach. Instead, the light here looks like our twilight on land. The deepest part of the ocean is called the aphotic zone, or deep sea. The water here is awfully cold, completely dark, and low in nutritional content. The deep sea comprises 80% of all the habitats on earth, which makes it the largest habitat on the planet. (source) Within those three zones, the ocean is divided up even further into five layers, which we saw in our book, and each is home to different varieties of marine animals. Let’s learn the layers and the types of animals that live there with this activity. (If you don’t have empty spice jars that will stack, you can use stacking plastic containers, like these. If you don’t want to purchase the figurines, you could draw or print pictures of the animals and tape them to the outside of the containers so they show through.)

Activity 2: The ocean is made up of salt water, which is denser than the fresh water we drink. What is the definition of density? Basically, density is how compact an object is. Put another way, density is the mass of an object divided by its volume. We’ll learn more about mass and volume below. (source)

How do we know the salt water is denser than fresh water? Let’s prove it with this simple egg and water density experiment.

What’s going on with this experiment? The egg in a cup of tap water will sink to the bottom because the density of the egg is higher than the density of tap water. But, if you add enough salt to the water, the egg will actually float back up to the surface! Adding salt to the water increases the density of the solution because the salt increases the mass without changing the volume very much. (source)

Activity 3: The saltiness of the ocean is also a big part of why it never freezes! Let’s answer the question, “why doesn’t the ocean freeze”, in a hands-on way with this STEM activity.

Lesson 2:

One of our favorite residents of the sea is the sea turtle! Let’s learn more about these remarkable creatures in the book One Tiny Turtle (or read it here on OpenLibrary). You can also watch this brief documentary for some more sea turtle information.

Activity 1: Let’s review the life cycle of the sea turtle with a hands-on ocean and beach model. Begin by setting up your diorama with blue (for the ocean) and white (for the beach) kinetic sand in a sensory bin or large baking dish. You can also use rocks, shells, sticks, or any other materials to build out your model. You will also need the sea turtle life cycle figurines from your set, and use small white rocks or dried beans for your eggs. (Save your model after this activity—we’ll add to it later in the week!) Here’s an example of how it might look:

Next, have your child act out the following parts of the sea turtle life cycle while you read:

  • A female sea turtle leaves the ocean to nest on a beach every two to three years. She then finds a safe spot to dig a deep nest in the sand where about 100 to 150 eggs are laid. Once filled with eggs, the nest is called a clutch.
  • After the eggs are laid and covered with sand, the mother walks away from the nest forever. A clutch is incubated in the nest for about 60 days.
  • Finally, the eggs hatch. Hatchlings use a temporary tooth called carbuncle (temporary egg tooth) to help break open the shells. It takes three to seven days to dig their way through the sand to the surface.
  • Once they emerge from the nest, the hatchlings find water. The journey from the nest to the beach is a real challenge. They are under threat of predators like birds, snakes, dogs, crabs, and even humans. Once they reach the water they will swim continuously, known as a “swim frenzy.”
  • Once they make it to the water, the turtles dive below the waves and ride the underflow out to sea. For the next 24 to 48 hours they work hard to descend to the depths of the ocean where they will continue to grow for decades into adult sea turtles.

Activity 2: Let’s use our sea turtle’s arduous journey as inspiration for a game! Print this “Sea Turtle Chutes + Ladders” board on cardstock and laminate, if possible. Use whatever playing pieces you have on hand and a die. Take turns rolling the die to try to get from 1 to 100. If you hit the top of a piece of kelp, your sea turtle gets tangled and slides down to the bottom of the ladder. If you hit the bottom of a wave, ride it up to a higher number! The first one to get to 100 wins! (If your child has a shorter attention span, use two dice to get to 100 faster.)

Activity 3: Baby sea turtles have to survive a variety of challenges to get to the ocean, including the elements! Let’s make a sun shelter for our own baby sea turtles with this STEM activity. You can make a sea turtle out of pipe cleaners and the UV-sensitive beads with this tutorial.

Lesson 3:

It’s Shark Day! Today, we’ll take an up-close look at these often misunderstood stars of the sea. Begin by reading the book How to Survive as a Shark.

Activity 1: For our activities today, we’ll explore some pretty nifty abilities sharks possess! For example, have you ever wondered how sharks float? Most fish have an air-filled swim bladder that keeps them from sinking, but the shark doesn’t (that’s how it can change depths quickly without damaging any internal organs). One thing that helps the shark? A large, oil-filled liver! Let’s find out why that helps the shark float with this buoyancy activity.

Activity 2: Shark scissor practice.

Activity 3: Most sharks have 2-3 rows of teeth, with up to 15 rows! But their teeth do not have roots like ours do, so they break off easily. Fortunately, the shark’s mouth moves new teeth forward like a conveyor belt as needed. As a result, they can have up to 50,000 teeth in a lifetime! (source) Let’s bring this to life with a little math practice. Start by printing this shark mouth (and laminating, if possible). Using playdough, fill the shark’s mouth with 20 teeth. Have your child count the teeth to confirm the number. Next, tell them a story about a shark who keeps losing and growing teeth! Give them a number of teeth to lose, and have them pull out the playdough teeth. How many teeth does the shark have now? Next, have him “grow” a certain number of teeth and have your child work out the sum as they add in more playdough teeth.

Activity 4: Want to learn more about the types of sharks that exist? Print the cards in this post and use them to play a memory game or for today’s copywork.

Lesson 4:

For today, we’ll be learning about some other amazing creatures found in the ocean. If you have the book The Big Book of the Blue, you can refer to the pages we’ll mention below for more information. There is lots to learn in this book, so be sure to give your child time to explore it as much as they want to!

Activity 1: Of course, one thing you can always find in the ocean is fish! In fact, scientists estimate that there are over 3,500,000,000,000 fish in the ocean! (source) Does your child ever wonder how all those fish breathe under water? Let’s learn more about it in this video. (You can also read pages 10 and 11 in The Big Book of the Blue.) Next, let’s bring this to life with a simple activity. Take a paper or plastic cup and cut out the bottom to create a cylinder. Cover one end of the tube with a coffee filter and secure with a rubber band. Next, take another cup and fill it with water and add a tablespoon or two of ground coffee (or dirt). Your set up should look like this:

Explain to your child that the cylinder represents the fish, the coffee filter represents the gills, and the coffee grounds represent the oxygen in the water. Pour the coffee water through the cylinder so that the coffee will get caught in the filter. Explain that in the same way, when the fish swallows water, the oxygen is caught by the gills to be distributed to the rest of the fish’s body. This is how fish breathe under water!

Activity 2: Perhaps the most impressive ocean resident is the blue whale. In fact, the blue whale is the largest animal on the entire planet. Let’s learn more about them in the book The Blue Whale (or listen to this read aloud). You can also read more about whales on pages 22 and 23, and the krill they eat on pages 30 and 31. Next, let’s bring that giant blue whale to life! Huge measurements can be very abstract for young children, so use this STEM activity to bring the size of a blue whale down to a concrete level.

Activity 3: What has no brain, no blood, no heart, and can sometimes glow in the dark? A jellyfish! You can read more about these fascinating creatures on pages 18 and 19 of The Big Book of Blue, or watch this video. Next, let’s make our own beautiful jellyfish with this craft.

Lesson 5:

There are so many different kinds of scientists who study the ocean. Let’s learn about one oceanographer (or a scientist who studies physical and biological aspects of the seas) who isn’t very well known but made major contributions to better understanding the ocean in the book Solving the Puzzle Under the Sea (or listen to this read aloud). You can also show your child the map originally drawn by Marie Tharp and Bruce Heezen here.

Activity 1: The “soundings” Marie Tharp used to map the ocean floor function much like echolocation, or the use of sound waves and echoes to determine where objects are in space. Read through this article with your child to understand how some animals (including dolphins and whales) use echolocation. Next, let’s set up an activity to demonstrate how sound waves can bounce. You’ll need a large aluminum baking dish and two toilet paper rolls. Lean the baking dish against a wall so it opens out. Next, give your child one of the paper towel rolls and have them hold one end facing the dish and one end to their ear. Next, you hold the other tube facing the dish and whisper into it. Does your child hear the sound bouncing off the metal dish and back to them? This is how echolocation works! Take turns so your child can try whispering while you hear their “secret” message.

Activity 2: Let’s think like a scientist for this next activity as we learn more about air and water pressure.

Activity 3: As we learned in our book, the ocean is massive and still holds many secrets humans have yet to discover. In fact, scientists are making new discoveries all the time! Share this article with your child about a huge coral reef only recently discovered near Tahiti. Next, watch this video to learn more about coral reefs, an important ecosystem found in the ocean. Finally, let’s add our own coral reef to our ocean model using these colorful noodles. (Here’s a picture to inspire their own creation, if desired!)

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Published by The Learn + Live Letter

The Learn + Live Letter is a play- and project-based homeschool curriculum for children ages 3-12.

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