Ocean Unit Science Experiments on Salinity and Water Temperature

Salinity and Water Temperatures Influence the Oceans’ CurrentsOcean Unit - Water Experiments

We just love hands-on activities! They are what make our units come alive! In this portion of our Ocean Unit, we did a number of experiments to show how salinity and water temperatures influence the oceans’ currents.


Our first experiment was on salinity.  In this experiment we talked about how salt changes the density of water.  One jar had no salt and the other jar had a lot of salt mixed in. Then we dropped pony beads into the water.  After a moment or two, the beads in the salt-free jar fell to the bottom while the ones that were placed in the salty water continued to float.

Salinity Experiment - Ocean UnitAfter that, we pulled out the dye and an index card to do the next experiment… how do plain water and salt water interact?  We dyed the salt water red and the plain water blue.  The first time we did this, the plain water was placed on top.  We placed an index card on top of the blue, plain water and flipped the jar upside down.  We then slid the index card out. (Note: We took a little too long and the index card started to rip. After that we placed the index card in a Ziploc bag and everything went smoothly!)

As you can see, the plain water remained separate from the salt water.

When we did the experiment in reverse with the salt water on top, the salt water and plain water immediately began to mix.

Salinity Experiment - Ocean ActivitiesOcean Currents: Warm Water – Cold Water Ocean Science Activities

Cold Water – Warm Water Experiment

For this next activity, we put yellow food dye in warm/hot water and green water in very cold ice water (with no ice included).  First, we had the warm water on top. We placed an index card in a Ziploc bag, placed that over the warm water, flipped it upside down and put the jar on top of the cold water.

When we removed the index card, the warm water stayed separate from the cold and did not mix. (See the yellow-green picture below left!)

Next, we placed the cold water on top.  As soon as we started to remove the index card, the cold and warm water started to mix.

Warm Water - Cold Water Ocean ActivityWe did a similar experiment to actually “see” cold water currents in action!

For this activity, gather a paper cup or water bottle, duct tape, dye, and a clear plastic container (or glass bowl). You’ll need warm water and ice as well.

We did this activity twice. The first time we used a clear glass bowl and a paper cup.

The paper cup was taped to the side of the bowl making sure that the cup was well above the water line. We filled the glass bowl with warm water. Then we carefully poured cold ice water into the cup.  We took a meat skewer and poked a hole in the bottom of the cup.

We observed what happened. The cool water streamed out of the cup and then pooled along the bottom (not mixing with the warmer water above).

Ocean Current ActivityThe second time we did this activity, we had a different purpose in mind. Instead of looking at the density of the cooler water, I wanted the kids to understand how water can flow in two different directions like surface currents and deep currents do in the ocean.

This time we used a huge plastic container with warm water. We poked a hole in the bottom/side of a plastic bottle and temporarily plugged it with a bit of clay. We filled it with blue ice water. Then we attached the bottle to the side of the plastic bin. One of the kids took off the plug.  The cool blue water once again streamed out (as long as the water was higher in the plastic bottle).  The kids then took a straw and gently blew a piece of tin foil in the opposite direction along the surface of the water.

Ocean Activity Currents - Warm and Cold Water ExperimentWe talked about how surface winds can move the water in one direction, while deep in the ocean the water might be flowing slowly in another direction!

We watched a couple of videos about salinity and about ocean currents and also did several worksheets that are in our Ocean Unit.

Note: We talked about surface winds in our Weather Unit last spring.

Weather Worksheets - Global winds, jet stream, high and low pressure systemsRecently, I’ve been sharing some of the other activities & topics we’ve covered in our Ocean Unit. You can find more about this unit here:

Ocean Unit - Marine Habitats Coral Reefs Tide Pools Tides Currents Ocean Zones Bioluminescence Worksheets and more

Our units are PDF downloads.  If you have any questions, you can visit the Frequently Asked Questions Page or feel free to email me! ~Liesl

$8.99 Ocean Unit: Ocean Unit – Layers of the Ocean/Ocean Zone  visit the post or view image 1, image 2, image 3, image 4, image 5, image 6, image 7, image 8, image 9 This in-depth unit covers marine habitats, coral reefs, tide pools, water form words, features of the ocean floor, salinity, tides & the phases of the moon, ocean currents, fish & their special body features, bioluminescence and the ocean zones.  There are lots of hands-on activity ideas included too!

Be sure to check your PayPal email address for the download link. If you have any questions, feel free to email me! ~Liesl

NOTE: The Ocean Unit is included in the Biology Bundle of 5. (See this post).

Biology BUNDLE of 5 Units

When we covered Marine Habitats, we went into quite a lot of depth about coral reefs. You can read more about that portion of our unit here: Coral Reefs

Corals and Coral Reefs Worksheets - Notebook Pages and Lapbook Activity

We then talked about the features of the ocean floor. From there we went on to talk about old-time navigation techniques.

Features-of-the-Ocean-Floor-WorksheetsFeatures of the Ocean Floor WorksheetsOcean Floor Mapping ActivityMy daughter really enjoyed this section on latitude and longitude.

Latitude - Longitude Activities and WorksheetsShe did a few activities using an “astrolabe” and a compass.  Obviously, it was not nighttime, so instead of finding Polaris and determining her bearing, instead she found where north was and then figured out where the north star would be.  Knowing that, we then went out in the evening to see if she was right based on the tools she used. 🙂

Astrolabe and Compass Ocean ActivitiesWhat is latitude - Longitude What is the Prime Meridian Tropic of Cancer Tropic of Capricorn

In our ocean studies we explored

  • Marine HabitatsOcean-Unit-100 Pages Marine-Habitats-Ocean-Currents-Tides-Bioluminescence
  • Coral Reefs
  • Tide Pools
  • Water Form Words (bay, estuary, lagoon, fjord, etc.)
  • Features of the Ocean Floor (trench, seamount, guyot, etc.)
  • Ocean Navigation (early navigation with astrolabes & the Ocean Unit - What causes tides - spring neap tide worksheetsconstellations, modern SONAR)
  • Salinity
  • Tides
  • Ocean Currents (Surface & Deep Sea Currents)
  • Ocean Life:
    • Special Body Features
    • Fish Body Shape and Movement
    • Biological Interactions: Mutualism and Commensalism in the Ocean
    • Ocean Zones - Layers of the Ocean ActivityDeep Sea Life – Bioluminescence, Anglerfish
  • The Ocean Zones
  • There are lots of hands-on activity ideas included too!

We also talked about the ocean zones and different layers of the ocean again (which we covered three or four years ago).

Ocean Unit : Again, for more information you can visit this post: 100+ page Ocean Packet. It is well over 100+ pages at this point and keeps growing as I add in this-and-that! It covers marine habitats, ocean zones, ocean features, tides and other topics.  :) ~Liesl

Ocean-Unit-100 Pages Marine-Habitats-Ocean-Currents-Tides-Bioluminescencehttps://homeschoolden.com/wp-content/uploads/2016/04/Marine-Habitat-Worksheets-Cards.jpgCoral Reef Notebook Pages - Worksheets

Ocean Unit - Water Form Words WorksheetOcean Unit - what causes tidesOcean Unit Study

In addition, we are watching the amazing documentaries  Blue Planet: Seas of Life and Blue Planet 2 (affiliate link) which are also available to watch on Amazon Prime.

Again, if you are interested in our Biology BUNDLE, visit this page:

Biology BUNDLE of 5 UnitsBiology BUNDLE of 3 - Biology - Taxonomy - Ocean Unit

See you again soon here or over at our Homeschool Den Facebook Page! Don’t forget to Subscribe to our Homeschool Den Newsletter. You might also want to check out some of our resources pages above (such as our Science, Language Arts, or History Units Resource Pages) which have links to dozens of posts.  You might want to join our free Homeschool Den Chat Facebook group.  Don’t forget to check out Our Store as well. :) Homeschool Den StoreAgain, if you are interested in joining our Homeschool Den Newsletter, feel free to subscribe here.

The Welcome Series includes 5 packed emails… with tips on homeschooling, keeping motivated, finding various resources and freebies tucked away on the blog and more!

Plus, you’ll be the first to hear about new packets (generally offered at a discount when they are first released), seasonal resources and more!

SubscribeHappy Homeschooling! ~Liesl

Disclosure: Please note that some of the links in this post are affiliate links, and at no additional cost to you, I will earn a commission if you decide to make a purchase.

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