How much salt is in the ocean?

How much salt is in the ocean?

Lesson narration:
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DISCUSS:

What is in the ocean water?

List as many different types of things as you can.

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DISCUSS:

We can’t see the salt in ocean water.

How could we figure out if there’s really salt in ocean water?

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01/20
Find a partner. Decide who will be the Wave Maker and who will be the
Salt Boss. If you’re working alone, that’s okay too. You’ll do both jobs.
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02/20
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Put the piece of black paper on your plate. Put the bag that will hold
observe what’s happening in your Tiny Ocean.
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Wave Maker: Open the bag and hold it open. Salt Boss: Put the ¼ cup
of water into the bag. Then add one teaspoon of salt. Wave Maker:
Zip the bag closed. Salt Boss: Make sure it’s REALLY closed!
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Wave Maker: Lay the bag on the black paper. Both: Notice what you
see in the bag and what you can feel through the bag.
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Wave Maker: Rock the bag to make waves, then lay it on the paper.
Salt Boss: Check the bag. If you see or feel salt, ask Wave Maker to
make more waves. Check again. Repeat until the timer runs out.
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Think about what the water in your Tiny Ocean looked like right after
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Salt seems to vanish when you add it to water and mix it up. People
say salt dissolves in water. Here are some people with different ideas
about what happens when salt dissolves in water. Discuss:
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To make your Tiny Ocean as salty as the pink lagoon at Cabo Rojo,
add another teaspoon of salt. Make waves until the salt dissolves
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You added two teaspoons of salt to your Tiny Ocean, but you
probably can’t see or feel any salt in the water. If you do see any salt
in the water, it’s a lot less than the two teaspoons you put in. Discuss:
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Maybe you thought about drinking the water to find out if it tastes
salty. We tried it for you—it’s salty! This is evidence that some salt is
in the water, even if we can’t see it. But how much salt is there?
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Here’s our idea. We could use a scale to measure the weight of the
water, the weight of the salt, and the weight of the mixture of salt
and water. Discuss:
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Suppose we compare the weight of the ingredients with the weight
of the mixture. What will happen to the weight of the water when we
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Let’s look for evidence to support any of these arguments. You put
¼ cup of water into your Tiny Ocean. Check the scale, then record
the weight in grams by #3 on your worksheet.
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You put two teaspoons of salt in your Tiny Ocean, so we’ll weigh
2 teaspoons of salt. Check the scale, then record the weight in
grams by #4 on your worksheet.
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To graph the weight of the water, find #3 on your worksheet. That’s
where you wrote the water’s weight. Draw a line to mark 60 grams.
Then draw a rectangle with that line at the top and shade it in.
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To graph the weight of the salt, find #4 on your worksheet. That’s
where you wrote the salt’s weight. Now that you know how to do it,
draw a bar on your graph to show the weight of the salt.
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added salt to the water. Each one drew a bar to show what they
think the mixture will weigh. Look at their graphs. Discuss:
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Now let’s see what the mixture weighs. We’ll make a Tiny Ocean, just
like yours. Check the scale, then write the mixture’s weight by #5 on
your worksheet and draw a bar showing the mixture’s weight.
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If you need a natural stopping point!

Teachers: If you are short on time, this is a good stopping point. Your students can make their Paper Bag Landscapes in a future session.

If you’re continuing right now, advance to the next slide.

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DISCUSS:

How could you take the water out of ocean water?

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01/04
will share. Here’s our Paper Bag Landscape. Imagine this is a real
landscape that you are flying over in an airplane. Discuss:
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02/04
Take turns going to the Paper Bag Landscape that your teacher has
made. With your partner, choose a spot for a Tiny Ocean. Put your
initials in that spot. While waiting your turn, discuss with your partner:
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03/04
When everyone has chosen a spot, take turns using your teaspoon to
put two teaspoons of Tiny Ocean water onto the spot you chose.
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Now you’ll have to wait while the water evaporates.
Teacher: Put the landscape in the sun to speed things up.
Watch the next video.
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# Extensions
Below are ideas for extending this topic beyond the activity and exploration you just completed.
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#Activity: What Happens When You Add More Salt?

Ask your students: What do you think will happen if we keep adding salt to the Tiny Ocean? Then try the experiment:

• Following the same steps you used to make your Tiny Ocean, add and mix in more salt, one teaspoon at a time.
• At some point, the salt will no longer dissolve in the water. A chemist would say that you now have a saturated solution.
• Predict what will happen if you let the saturated solution dry out on your Paper Bag Landscape.

Try the experiment and see if you were right!

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The following readings are free from Wonderopolis.

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# Videos

Check out these Mystery Science Mini-lessons. Each has a 5-minute video with a bonus of 5 amazing visuals guaranteed to spark curiosity and discussion about salt.

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# Simulation: Dissolving Sugar in Water

This app from Smithsonian in The Classroom uses a model to explain what happens when sugar dissolves in water and when water evaporates.

• Open the app. You’ll start with an empty hummingbird feeder. To the right of the feeder, notice the circles that show particles of air and water. The air contains just a few particles of water.
• Use the button to add water to the hummingbird feeder and watch what happens in the circles.
• Add sugar, and you’ll see sugar particles in the water. Evaporate the water. Do you notice any changes in the air?
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salt water

1 of 12

water with salt in it, such as the ocean
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ocean

2 of 12

a large area of salt water that covers the Earth
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dissolve

3 of 12

when one substance mixes with another and it looks like it disappears, such as when sugar mixes into tea
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mixture

4 of 12

a combination of two or more things
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solution

5 of 12

a special kind of mixture where you cannot tell the different parts from each other
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evaporation

6 of 12

the process of a liquid changing to a gas
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model

7 of 12

a pretend version of something that scientists use when the real thing is too big, small, or complicated to work with
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observe

8 of 12

to pay close attention to something
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measure

9 of 12

to describe something using numbers that can be compared
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graph

10 of 12

an image that helps you understand information
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property

11 of 12

something you can observe about an object or material
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evidence

12 of 12

information that can be used to support or reject an idea
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Lesson narration:

Activity Prep

Print Prep

In this lesson, students explore how incredibly salty the ocean is, even though we can't see the salt! In the activity, Tiny Ocean, students create a model ocean to observe how salt seems to completely vanish when dissolved in water. Students then measure and graph quantities of the water and salt to provide evidence that, even though we can’t see it, the salt still weighs the same amount. Students also create a model salt flat, allowing the water to evaporate, leaving the salt behind.

Preview activity
Exploration

10 mins

Hands-On Activity

Wrap-Up