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The Science

Behind

Popping Boba

1.1 What is popping boba

made of?

turn and talk

In this lesson, we’ll be
exploring popping boba.

Have you ever had boba
before? What types and
flavors?

initial ideas

What is popping boba and how is it made?

Directions:
1.Complete part 1 based on your own
prior knowledge and observing the
store-bought boba.
-What is the texture like?

-What does it reminds you of?

2.

Add any curiosities or questions in the
“explore” box. Try to have at least ONE
by the end of the class.

popping vs. traditional boba

There are different types of boba.

Optional: To learn more about different

types, read “What is popping boba” in the

Popping Boba Anchor Reading.

popping vs. traditional boba

Popping Boba:

Gel exterior

Juice interior

“Pops” when
some force is
applied

Traditional
Boba:

One texture

Chewy

Doesn’t pop
with force

google forms: pre-lesson

Let’s consider what we already know.

Directions:
1.Go to provided google form link.

2.

Click “before” for the first question.

3.

Answer the questions to the best of
your ability.

You are not expected to
know the answers to these
questions yet. It’s okay to
be unsure or wrong. We’d
rather see you take a risk!

This slide is only intended for teachers part of our Science and Cooking for Secondary Educators Program.

ingredients in popping boba

Two key ingredients in most
popping boba are calcium
chloride (or calcium lactate)
and sodium alginate.

ingredients in popping boba

Two key ingredients in most
popping boba are calcium
chloride (or calcium lactate)
and sodium alginate.

How could we further explore
what these ingredients are?

unpack

1.Write down sodium alginate in one box
(left) and calcium chloride in the other
box (right).

2.

Read “What makes up popping boba?”
in the Science Behind Boba Anchor
Reading and complex the “unpack” box.

Sodium Alginate

Calcium Chloride

debrief

2. Unpack: What are two key ingredients in popping boba?

Name:

Chemical Formula:

Positive Ion:

Negative Ion:

Name:

Chemical Formula:

Positive Ion:

Negative Ion:

debrief

Alginate is a polyatomic ion.

What does that mean?

debrief

A polyatomic ion is an ion that is made of
more than one atom.

●poly= many

●atomic= atom

Together, this group of atoms makes
up a single ion and carries a negative
(1-) charge.

We’ll explore other examples next
class.

Learn more here.

debrief

The ratio of calcium:chloride is 2:1 in calcium
chloride.

Why is this?

reviewing atomic structure

Let’s walk through why calcium chloride
has this formula by analyzing the atomic
structure and properties of calcium and
chloride ions.

Directions: Complete “Breaking Down
Calcium Chloride in Popping Boba” in
your handouts.

1.2 What happens when

we combine sodium
alginate and calcium

chloride?

frame

Today we will be looking at calcium chloride and sodium
alginate.

How do you think calcium chloride and sodium alginate
behave in water?

Try to backup your idea with reasoning.

exploring ionic compounds

Directions: Complete “Exploring
Different Ionic Compounds”.

Here, you will…
●identify the charges of ions and
the ratio of ions in different ionic
compounds

●look at examples of polyatomic
ions

●look at how these different ionic
compounds behave in water
(through a PhET Interactive)

exploring ionic compounds

How to set up your PhET
Simulation:

1.Click the “micro” tab.

2.

See more solutes by
clicking the arrow.

3.

Click and move the
shaker to add it to
water.

model

Based on what we learned, let’s
begin to develop a model of
calcium chloride and sodium
alginate solutions.

Directions: Complete box 1 and 2
in “particulate level”.

We will add in details about
“macroscopic level” after your
lab.

lab

Directions: Complete Lab: What
happens when we combine
sodium alginate and calcium
chloride?

In this lab, we will analyze the
properties of each substance
and then combine them to
observe what happens.

post-lab

Only watch this
video after
completing the
lab. This shows
the results!

post-lab

What do you think the gel-like
substance may be? Specifically
on a particulate level?

It’s okay to be uncertain! Try to
backup your thinking with
evidence and reasoning.

1.3 Why did a gel form?

model

Today we’ll be focusing in on
the substance that was
created when we combined
sodium alginate and calcium
chloride.

Begin by describing what you
saw on a macroscopic level.

model

Now let’s go back to what we
discussed in the post-lab.

Let’s first discuss…

-What could the substance be?
-List all the possibilities.

-What properties and data do
we have to draw on to help
us?

what could the gel be?

This substance could be a
variety of things. Look at the list
of possibilities.

Discuss with your partner which
substances you think we can rule
out. Explain your thinking.

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

what could the gel be?

The fact that this gel is insoluble in liquid
suggests it is not an ion.

Considering their electron configuration
and charge, we can rule out any
substances that are made of ions with
the same charge (e.g. two positive ions
cannot bond ionically).

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

what could the gel be?

The fact that this gel is insoluble in liquid
suggests it is not an ion.

We may recognize sodium chloride as
table salt- and draw on our previous
experience that when we add salt to
water, it does not gel. It is soluble and
dissolves.

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

what could the gel be?

If calcium alginate forms, what would
its chemical formula be?

Look at your notes to look at the
molecular structures of calcium and
alginate. Then consider what type of
bond would form.

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

what could the gel be?

The chemical formula of calcium
alginate is Ca(C6H10O7)2

Take a moment to turn and talk to
explain why this ratio of ions exists.

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

read

Directions: Read “Gels and
Crosslinking” in the Science
Behind Popping Boba Anchor
Reading.

As you read, take jots about
anything you think helps us
answer the question: What is the
gel? How and why does it form?

simulation

In this next activity, we are going to
further explore how charges affect
attraction.

Directions: As we go through the
simulation, take notes in your handout in
the “simulation takeaways” box.

simulation

Directions: Go to this simulation.

1.Setup: Remove the checkbox that says
“show electric field.”

2.

What do you notice occurs in the electric
field and forces between charged particles
when you change the charge value?

3.

Compare sodium alginate and calcium
alginate:

a.

Mimic sodium alginate: Set Particle B to
-1 and Particle A to 1.

b.

Mimic calcium alginate: Change
Particle A to 2.

Click to go
to the

interactive!

crosslinking

Why does crosslinking occur?

There are strong electrostatic
attractions between calcium
ions and alginate strands.

Why? They are oppositely
charged ions.

crosslinking

Why does crosslinking happen?

Calcium ions have a +2 charge. This is
important because it means…

-They displace the sodium ions. They
have a stronger attraction/pull (+2
charge vs. +1 charge).

-They can interact with multiple
alginate strands. This creates a
crosslink between strands.

This locks the alginate strands together in
a web, or gel.

displace

Attract and crosslink

crosslinking

In the reading, you see an
analogy about beads. Let’s look
at another one!

Before it gels, it’s as if the
alginate strands are like pasta
or noodles.

They slip by each other easily.

crosslinking

When we mix the
substances, we create
sticky points between the
noodles.

Imagine we added
something sticky to stick
certain noodles together
at certain points.

How would this change
how they move?

crosslinking

They move less easily.

It’s the same idea
when we combine
sodium alginate and
calcium chloride.

The molecules are in a
gel and cannot slide
past each other.

“sticking” points
restricts free flow
movement

centimeter

crosslinking

These sticking points caused by strong
electrostatic attractions are sometimes
referred to as crosslinks or bridges.

Within our beads analogy, these
bridges are probably about a few
centimeters long.

Within our noodles, these bridges are
probably about a millimeter long.

With our substances, these bridges are
about a nanometer long.

It’s all about scale.

nanometer

millimeter

what else?

So far we’ve spent our focus
solely on the gel.

Was anything else formed in this
chemical reaction?

Consider what we started with:
sodium alginate and calcium
chloride.

Possible Products:

-Calcium (Ca2+)

-Sodium (Na+)

-Alginate (C6H10O7)-

-Chloride (Cl-)

-Calcium Alginate

-Sodium Chloride

-Calcium Sodium

-Alginate Chloride

what else?

modeling activity

Get in a small group and make a model.

How can you represent the cross-linking that is going on?

Let’s apply what we have learned to
consider if we could use other ionic
compounds in place of calcium
chloride.

Directions: Complete the Google
form, “What else could we use to
create a gel?”

assess

google forms: mid-lesson

Let’s consider what we already know.

Directions:
1.Go to provided google form link.

2.

Click the appropriate section for the first question.

3.

Answer the questions to the best of your ability.

This slide is only intended for teachers part of our Science and Cooking for Secondary Educators Program.

1.4: How do we create a gel
coating and keep the inside

of the sphere a liquid?

Day 1: Lab

Directions: Identify and
explain what types of
bonds are present in
calcium alginate and
sodium chloride, as well as
in the products formed in
this reaction.

review

So we have seen how we can create a
gel, which is one important component
to popping boba. But is it the only
component?

How is the popping boba different from
our gelled product?

initial ideas

Directions:

1.Go to the handout: How do we create a
sphere with an outer gel layer?

2.

Complete the observe section to
compare products we’ve seen.

Be ready to share out.

observe

observe

Gel Blob

Sphere with Gel
Layer

How can we create a sphere that only has
the outer layer gelled?

Directions: Jot down your initial ideas in
the first unpack box.

initial ideas

gelled

not gelled

By controlling and
manipulating the way we
add sodium alginate to the
calcium chloride bath, we
can create a sphere.

Watch the video to see what
you will do.

lab (part 1)

Now we know how to form a sphere.

But how can we control the thickness
of the gel layer?

lab (part 2)

Directions:

1.Briefly answer the question now having
completed the lab.

2.

Consider: How can we control how thick the
gel layer is?
a.

Fill in the blank to write out the
question.

b.

Jot down initial ideas.

initial ideas

thick

Thick gel layer

Thin gel layer

In this lab, you will let the sodium alginate sphere
sit in the calcium chloride bath for different
amounts of time. You will use a teaspoon (not a
dropper) to add in the sodium alginate.

Directions:

1.Complete the pre-lab to consider…

●how using a teaspoon is different than
using a dropper (like the previous lab)

●Predict what you think will occur

2.

Complete the lab.

lab (part 2)

Directions: Complete post-lab questions.

Then we will discuss what you noticed
next class.

post-lab

Day 2: Unpack

Why do you think this happened? What is going
on on a particulate level to explain these results?

Directions: Go to the handout: How do we
create a sphere with an outer gel layer?

1.Briefly re-answer the question: How can we
control how thick the gel layer is? In the
“after the lab section” of your chart.

2.

Jot down initial ideas to consider what is
going on a particulate level.

Be ready to share out.

review + initial ideas

thick

Share Out: Why do you think this happened?
What is going on on a particulate level to explain
these results?

share out

thick

read

Directions: Read “Gelling &
Diffusion” in the Science Behind
Popping Boba Anchor Reading.

Add jots to your “reading” and
“model” box.

watch

Directions: Watch
3:27-4:37 of the video.

Turn and Talk: Why does
the amount of time the
sphere sits in the bath
matter?

whiteboard

What was different about these trials?

whiteboard

30 seconds

1 minute

3 minutes

review

Diffusion: movement of particles in a
liquid from high to low concentration

Calcium ions surrounding the drop
diffuse into the drop. As they do this,
crosslinking occurs.

A variety of factors can influence the
speed and degree at which this
occurs.

diffusion

Wait, so is only calcium diffusing here?

However, some move more
quickly than others.

Smaller molecules move, or
diffuse, more quickly. Here, the
difference in size is HUGE.

In reality, all particles in the liquid are diffusing.

Directions: With a small group on
a large piece of paper, develop a
model to show and explain what
the inside and outer layer looks like
on macroscopic and particulate
level.

Your model should…

●Include both the outside layer
and inside

●Explain what impacts the
thickness of the gel layer and
why

model

Outside
Layer:

Inside:

model

Outside:

Inside:

1.5: How can we make a
flavored popping boba?

frame

Today we will make flavored popping
boba. This is a two part lab.

In part one, you’ll make your flavored
mixture and do a brief test.

In part two, you’ll design your own
experiment to determine how long the
sphere should sit in the bath for the
ideal texture.

frame

Option 2 (more complex):
How will changing the concentration of
calcium chloride affect the final
process and product?

What we’ve been using: 1% calcium
chloride solution

What happens if we use…
0.5% calcium chloride solution?
2% calcium chloride solution?

lab

Directions:
1.Take ~10 minutes to complete part 1.

2.

Once done with part 1, begin to plan
your experiment for part 2 by
completing steps 1-4.

3.

Once you have completed step 4,
have your designed experiment
checked before you move onto
completing it.

lab

Directions: Once you have
completed part 2 of your lab,
complete the post-lab questions.

review

How is popping boba made?
Review what we have learned so
far!

Use your notes and the Science
Behind Popping Boba Anchor
Reading for help.

google forms: post-lesson

Let’s consider what we have learned.

Directions:
1.Go to provided google form link.

2.

Click “after” for the first question.

3.

Answer the questions to the best of
your ability.

This is your opportunity
to show what you have

learned.

This slide is only intended for teachers part of our Science and Cooking for Secondary Educators Program.

alternate lab

lab: apple popping boba

Directions:
Watch this
video, and then
complete
Lab 4: Apple
Popping Boba
by following the
directions in
your student
handout.

reflect

1.What was something new
you learned?

2.

What piqued your curiosity?