A Detailed Lesson Plan in Science
(First Year—Secondary)
I.
Objectives
At the end of the lesson, the students will be able
to:
A.
Describe the polarity of a water molecule and explain how that polarity affects the properties of water.
B. Explain why water climbs the inside of a thin glass capillary but not a
thin plastic capillary.
C. Describe a system whereby the components of a water-based substance
might be separated and discuss how this separation occurs.
D. Explain why oil and water don't mix.
E. Predict whether a substance, based on its hydrophilic and/or hydrophobic properties, will dissolve into water or oil.
II.
Subject Matter
The Properties of Water
Reference:
Science and Technology 1 by Scott
Materials: paper strips, detergent, wax paper, coins, glue,
cooking oil, red food coloring, cups of water, 10 ml grad cylinders, 50 ml
grad. Cylinders, beaker, glass slides, stirring rods, medicine droppers, scissors
Values:
Creativity, Patience, Following Instructions
III.
Procedure
A.
Learning Activities
Teacher’s Activity
“Good Morning Class...”
“Let us pray
first...”
(Checking of
Attendance)
...say
present...
“Please pick up
the pieces of paper
under your
chair”
“Have you ever
wondered what’s behind water?—not bodies of water, but the water itself, the
liquid, Everything in this world are made by God with their special functions...
Now let us discover what’s so special about water.
Presentation
Effects
of Detergent
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To Do
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1.
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With your finger, spread one small drop
of detergent
on the surface of a dry penny.
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Predict
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2.
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How many drops do you think this penny
will hold after being smeared with detergent,
more, less, or the same as before? Why?
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3.
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Specifically, how many drops do you
think it will hold?
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Table 2. Prediction of Number of Drops of Water on a Penny with
Detergent
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person
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#1
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person
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#2
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person
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#3
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person
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#4
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Average
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Discussion
Water covers about three fourths of the surface of the earth? It is
ubiquitous. It is also one of the simplest yet most important molecules in
living systems. It makes up from 50 to 95 percent of the weight of living
organisms. The cytoplasm of a cell is a water-based solution that contains
a variety of ions, salts, and molecules which make life 'happen.' Water is
literally involved in every facet of life.
Figure
2. Polarity of Water Molecule
The simplicity of the water molecule belies the
complexity of its properties. Based on its small size and light weight, one
can predict how it should behave, yet it
remains liquid at a much higher temperatures than expected. It also boilsand freezes at much too high, or low, of a temperature for a
molecule of its size. Many of these unexpected properties of water are due
to the fact that water molecules are attracted to each other like small
magnets (cohesion). This attraction results in turn from the structure of
the water molecule and the characteristics of the atoms it contains.
Each molecule of water is made up of two atoms of
hydrogen connected to one atom of oxygen, as shown below. This is
summarized in the familiar formula, H2O.
Figure
3. Hydrogen Bonding in Water
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Atoms are most stable when they have a particular configuration of
their outer shells, a concept which will be discussed in future labs. These
configurations explain why hydrogen in water will take on a partial positive charge and
why oxygen will take on a partial
negative charge. These partial charges cause water
molecules to 'stick' to each other like magnets. The 'stickiness' in this particular case is
due to 'hydrogen bonding'.
In this case, hydrogen bonding involves the attraction between the
positively charged hydrogen atom of one water molecule and the negatively
charged oxygen atom of another water molecule. As no electrons are actually
shared however, hydrogen
bonds are much weaker than covalent bonds - they easily
break and easily form again.
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Application
(Activity)
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1.
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Water moves to the tops of tall trees
due to capillary
action
combined with root pressure and evaporation
from the stomata (openings) in the leaves. Water will also climb up paper,
and often the migrating water will carry other molecules along with it. The
distance traveled by these other molecules will vary with their mass and charge.
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2.
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How fast do you think water would climb
a strip of absorbent paper about one-half inch wide?
about one inch per ____________________ (time)
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3.
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Obtain a 50 ml graduated cylinder, and
tear off a strip of chromatography paper that is just long enough to hang
over the side of the cylinder (inside) and reach to the bottom.
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Figure 6. 50 ml Graduated Cylinder with Chromatography Paper
& Ink
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4.
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Run the paper strip along the edge of a
scissors to take the curl out of it.
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5.
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Place a single small drop of ink from a
black vis-a-vis pen on the paper, about one inch from the bottom, and let
it dry completely.
Figure 7. Ink on Chromatography Paper
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6.
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Put 10 ml of water into the graduated
cylinder and place the strip of paper in the cylinder so that the bottom
end is immersed in water and the drop of ink is just above the surface of
the water. Fold the paper over the top side.
Figure 8. Close-up of Ink
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7.
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Note the starting time below.
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8.
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Watch and note the time at 5 minute
intervals. When the water climbs to the top of the paper, remove the paper
from the water, and let it dry.
Table 3. Time of Water Climbing
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Time (minutes)
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Distance (inches)
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0
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5
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10
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15
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20
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25
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30
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How did the ink change? Glue the paper
onto the page here, and label each color on the strip.
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Student’s Activity
“Good Morning Sir!”
(One Student will lead the
Prayer)
(Students raise their hand
and say present as the teacher calls in their name)
(Students pick up the pieces of paper)
(Students perform the activity)
(Students listen attentively)
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IV.
Evaluation
1. Predict what
will happen if you add a few drops of a water-soluble dye solution to each of
the above graduated cylinders containing water and oil. Will the dye mix with
the water, the oil, or both?
2. Add a few drops of dye to each cylinder.
Use a glass stirring rod to penetrate the interface between each layer, giving
the dye access to both water and oil. How does the dye behave in each cylinder?
Does it diffuse into the oil? Into the water?
V.
Assignment
“Why is liquid very
important not just to humans but to all the living things in the world? –Write
on 1 whole sheet of paper
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