Engineering
Mixtures:
Separation
Anxiety
SISSI 1 Grades 3-5
Essential Questions
 How
can properties of substances be
used to separate various mixtures?
 How can the Engineering Design Process
be used to find the most efficient
procedure for separating mixtures?
Separating Mixtures
1. How can you
separate any
two things that
are next to each
other?
2. How can you
separate items
made of iron from
items with no
iron?
4. How can you
separate items of
different sizes?
6. How can you
separate items of
different
densities?
3. How can you
separate things
dissolved in a
liquid? (the solute
from the solvent)
5. How can you
separate
dissolved items
from items that
are not dissolved?
7. How can you
separate
pigments or inks
from each other?
Magnetic attraction
separates magnetic material from a mixture of other
substances.
Example:
A cow magnet, is given to a cow to swallow.
It stays in the first part of the cow’s stomach,
keeping magnetic materials like wire and
other harmful materials that cows swallow
from going into the rest of their digestive system.
Evaporation
separates a solid that has dissolved in a liquid solution.
a. The solution is heated or left uncovered until all the
liquid turns to a gas (evaporates) leaving the solid behind.
b. Example:
Salt in salt water or ocean water, for example, is
separated by heating the solution until all the water
evaporates leaving the solid salt in the container.
Sifting
separates smaller solid particles from larger
solid particles.
Examples:
• Cooks sift flour to get a small particle size for
baking leaving larger particles of flour in the
sifter above the screen.
•
Sand and gravel companies, for example,
separate rocks into different sized particles for
road building and other construction projects
using this method.
•
Archeologists use sifters to find small artifacts in
the soil.
Filtration
used to separate solid particles from a liquid or gas.
a. Pouring the mixture through a filter paper in a funnel will trap
the solid particles and only allow the particles of the liquid to
pass through.
b. Example:
Water treatment plants use this as
part of the process for separating dirt and
other solid particles from water to produce
clean drinking water.
Flotation
separates solids that float from the remaining liquid
in a mixture.
a. The solids are stirred and when they float to
the top, they are skimmed off the surface of the liquid
and put into a different container.
b. Example:
This method is used in some water purification plants
by letting solids float to the top.
Chromatography
used to separate and analyze the solutes in a solution.
a. A small amount (2-3 drops) of the solution is put on a
piece of filter paper, which is put in a solvent.
b. The substances in the solution that dissolve most easily
travel the furthest; and substances that do not dissolve
easily do not travel very far.
c. Example:
Scientists use the bands of color that are formed
to identify the substances in the solution by
comparing them to the location of known
substances forming bands of color on different
filter papers.
Explore
Engineering Design Process
ASK: What is the problem? How have
others approached it? What are your
constraints?
IMAGINE: What are some solutions?
Brainstorm ideas. Choose the best one.
PLAN: Draw a diagram. Make lists of
materials you will need.
CREATE: Follow your plan and create
something. Test it out!
IMPROVE: What works? What doesn't?
What could work better? Modify your
designs to make it better. Test it out!
Explore
The Goal

A supply truck carrying diatomaceous earth to the Bright
Toothpaste Factory collided with a truck carrying iron filings to the
Magnificent Magnet Company. The collision happened on a
gravel road going through a salt marsh. The accident resulted in a
giant mixture of materials from the trucks as well as the ground
around it.

Fortunately, no one was hurt. Unfortunately, the mess needs to be
separated so that the valuable loads can get to their destinations.

A $1,000,000 clean-up contract will be given to the team that can
best separate the mess into the original substances!

Your goal is to find the most efficient method for separating the
ingredients in a mixture of gravel, diatomaceous earth, iron filings,
leaves/sticks, and salt. Each substance should be as pure as
possible and as close as possible to the starting amount.
Explore
Ask/Imagine
 What
do we know about the properties of
each of the ingredients?
 What do we know about ways to
separate various materials?
 Brainstorm ideas to separate the
substances.
Explore
Properties of Materials
1.
Use the materials in your tub to explore the
properties of gravel, diatomaceous earth,
iron filings, leaves and sticks, and salt.
small
small
small
Med/large
large
no
no
yes
no
No/yes
yes
no
no
yes
no
no
no
no
no
no
Explore
In a Ziploc bag, make a model of
the mixture caused by the truck
collision.
As you work, you may put together
another mixture if you need to.
Explore
Plan
 Talk
with your group to plan the methods
and the order that you will separate the
materials.
 Write your plan on your data sheet.
Explore
Create Improve Create Improve…



Use the materials in your tub to find the most
efficient way to separate your mixture.
As each substance is separated, measure its
mass in grams on the digital scale and place
it in one of the courtesy cups.
Improve the steps as you go. You may make
another bag of the mixture if you need to.
Record your results on the data sheet.
Evaluate
Communicate
 Choose
one person from your group to
report your results to the class.
Extend
Mixtures
Separating
Song
Success?