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Zoom
Glue
INTRODUCTION
 This activity will
demonstrate the concept of adhesives. Glue is the
common name for a variety of specificuse adhesives.
Students may also be familiar with other adhesives,
for example, cement, beeswax, and tar.
GRADE
LEVEL K – 6
OBJECT
OF ACTIVITY
Make glue from household ingredients and then test
its holding strength.
CONNECT
TO ENGINEERING
In real life, engineers design special glues when
they need to hold things like envelopes, sneakers,
and even airplanes together.
DISCUSSION
The first commercial glue, around 1750, was made
from fish. Other early adhesives used natural
rubber, animal bones, blood, starch, and milk
protein or casein. Today animal glues have mostly
been replaced with cheaper synthetic glues made from
manmade chemicals synthesized from petroleum and
natural gas. When milk and vinegar are mixed
together, the vinegar makes the protein in the milk
stick together to form small white lumps called
curds. The leftover liquid is called whey. The
youngest students may enjoy recalling the
“Little Miss Muffet” rhyme. When you add
glue between two pieces of paper, the glue seeps
into tiny cracks in the papers. When the glue
hardens, it forms a bond to hold the paper together.
Engineers design specific glues that will bond
specific surfaces.
MATERIALS
For each batch of glue:
-
1/2 cup
skim milk
-
2
tablespoons vinegar
-
2 large
paper cups
-
5 paper
towel
-
s rubber
band
-
plastic
spoon
-
1
teaspoon baking soda
-
3
tablespoons water
Activity
One: Making the glue
-
Put the
vinegar into the cup holding the skim milk. Stir
for about 30 seconds.
-
Make a
strainer to separate the curds from the whey. Put
a folded paper towel over one of the large paper
cups. Push down in the center to form a bowl
shape. Put a rubber band around the top of the
cup to hold the paper towel.
-
Pour the
curds and whey into the strainer.
-
Wait
about 5 minutes for all the whey to drip through.
Use a spoon to carefully scoop out the curds and
put them on a clean paper towel.
-
Put
another paper towel on top of the curds and
gently press down. Soak up the remaining liquid
until the curds feel firm, not squishy.
-
Put the
curds in a clean paper cup. Add about 2 teaspoons
of water to the curds and stir.
-
Add the
baking soda and stir.
-
Add small
amounts of water until your mixture looks like
glue. Students can use the glue to make test
loops, but the actual testing must be done with
pre-made loops.
Activity
Two: Testing the result
-
Have
testing loops prepared ahead of time to let the
 glue dry: use four
1” x 8” strips of paper. Make each
strip into a loop using different adhesives: ZOOM
glue, white glue, peanut butter, glue
stick.
-
With the
class, make a test bucket: poke holes on opposite
sides of a small paper cup and tie a string to
the holes for a handle.
-
Poke a
hole in each test loop; use a paper clip as a
hook to attach the bucket handle to the first
loop. Slide the test loop over a yard stick and
have 2 students hold the ends.
-
Drop
pennies one at a time into the cup until the
strip pulls apart. Count the pennies and record
results. Repeat for each test loop. How does the
ZOOM glue compare to the other adhesives?
FURTHER
EXPLORATIONS
Encourage students to try this at home.
Change one thing (the variable) about your glue
recipe. What happens if you use whole milk instead
of skim? What happens if you leave out the baking
soda? What happens if you use the glue on strips of
cloth? On plastic? You can also invent your own glue
out of different ingredients. Test the results for
each variable.
This
activity provided by WGBH Educational Foundation.
Used with permission. For more ZOOM Into Engineering
activities, go to http://www.discoverengineering.org.
ZOOM and the ZOOM words and related indicia are
trademarks of the WGBH Educational
Foundation.
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