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How much salt is in the ocean?

How much salt is in the ocean?
Lesson narration:
English Spanish
Scroll for prep
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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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Step
01/20
Find a partner. Decide who will be Wave Maker and who will be Salt Boss. If you’re working alone, that’s okay too. You’ll do both jobs.
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Step
02/20
Get your supplies.
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Step
03/20
Put the piece of black paper on your plate. Put the bag that will hold
your Tiny Ocean on top. Having a black background will help you
observe what’s happening in your Tiny Ocean.
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Step
04/20
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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Step
05/20
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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Step
06/20
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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Step
07/20
Think about what the water in your Tiny Ocean looked like right after
you added salt. Answer question #1 on your worksheet.
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Step
08/20
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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Step
09/20
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
completely. Then answer question #2 on your worksheet.
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Step
10/20
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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Step
11/20
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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13/20
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
add salt? These people have different ideas about that. Discuss:
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14/20
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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15/20
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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16/20
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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17/20
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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18/20
These people had different ideas about what would happen when we
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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19/20
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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Step
20/20
Discuss. Then answer question #6 on your worksheet.
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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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Step
01/04
You’ll start with a landscape made from a paper bag that your class
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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Step
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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Step
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.
While waiting your turn, discuss:
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Step
04/04
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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Slide Image
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Slide Image

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


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


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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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Slide Image

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


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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:
English Spanish

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
Number of students:

I have a Mystery Pack

Tiny Ocean worksheet 1 per student
Tiny Ocean Answer Key teacher-only resource 1 per class
Baking Sheet
1 per 8 students
Clean-up Supplies (Eg. Paper Towels)
1 roll per class
Black Construction Paper
1 sheet per group
Dixie Cups (3 oz)
2 cups per pair
Measuring Cup
Needs to have 1/4 cup measurement.
Details
1 per class
Paper Bag, Large
1 bag per 8 students
Paper Plates
1 plate per pair
Plastic Spoons
You can also use a teaspoon measuring spoon. If you use a plastic spoon, check to see how much salt it holds. If it measures significantly less than a teaspoon, we suggest using two spoonfuls in place of each teaspoon of salt.
Details
1 spoon per pair
Salt
2 teaspoons per pair
Ziploc Bags (Sandwich Size)
1 bag per pair
Prep Instructions

We suggest students work in pairs. Each pair will make a Tiny Ocean in a plastic sandwich bag.

We suggest four pairs of students (8 students) then work together in a group to add their Tiny Ocean to a Paper Bag Landscape. Homeschool students can work on their own.

Each Paper Bag Landscape needs to dry on a cookie sheet. So if you have 30 students, you will need enough space for 4 cookie sheets. See below for details.

Plan Your Time

If you have limited time, you can divide this lesson into two sessions.

Part 1 (create a Tiny Ocean) takes 35 to 40 minutes.

Part 2 (create a Paper Bag Landscapes) takes 15-20 minutes. Part 2 begins here.

Prepare Construction Paper

Cut each piece of construction paper in half so that each pair of students has 1/2 sheet.

Prepare Cups with Water and Salt

Divide your Dixie cups into two equal piles -- one for water, one for salt.

Pour ¼ cup of water into each cup in one pile.

Put a couple of teaspoons of salt into each cup in the other pile.

Prepare the Paper Bag Landscapes

Watch this video to see how we prepare the Paper Bag Landscapes.

Teacher Tip

After creating their Tiny Ocean, students will observe as their ocean dries, seeing the salt flat that is left behind. The time it takes for the Tiny Ocean to dry depends on humidity where you live. In Nevada, our Tiny Ocean dried in an afternoon. In foggy San Francisco, it took a few days.

Exploration

10 mins

Hands-On Activity

35 mins

Wrap-Up

20 mins

Extend this lesson

Vocabulary

Unit Reading

Activity

Mini-lessons

Online Simulation

Transcripts

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