Performing a discrepant event for the class is a bit like performing a magic trick. Mostly used in science classes, this is a great strategy for capturing student interest and engaging them in trying to figure out the “magic”. Typically, discrepant events are science demonstrations with a surprising event. Leaving students wondering what happened creates a state of cognitive dissonance, creating curiosity and stimulating critical-thinking skills. The key is the element of surprise. In addition, discrepant events engage the students with inquiry-based learning, teaching them to ask questions, form predictions, and explain results. This process stimulates higher-order thinking, such as problem-solving skills in a new and unfamiliar situation. The key is to engage students in asking questions and drawing observations to teach them to think like scientists. Many teachers use student journals to help students organize their thoughts in reasoning through the rationale behind discrepant events:
1. Candle under glass:
With and without a plant. The
flame will stay lit longer in glass with the plant.
Great way to demonstrate that
photosynthesis produces oxygen.
2. Hole in the bottle:
2. Hole in the bottle:
Poke a hole in the bottom of a 2L
bottle with water in it. Ask students to make prediction (water will come out
of the hole). When water does not, ask students how they could make water come
out of the hole. Help them figure out why water does not. Great way to
introduce students to the concept of gases and pressure.
3. “The Amazing Boiling Machine”:
Heat water in a flask until
boiling. Cool the bottom quickly by corking and putting flask on ice. Flip the
flask upside down and put the ice on top. Water should start boiling again.
Great way to introduce students to volume, pressure, and temperature (water
boils because cold temperature on part of flask with air decreases air
pressure).
4. Egg in a Bottle:
Ask students, “How can I fit an
egg (hard-boiled) into the bottle without breaking it?” Put strips of paper
into bottle. Light the paper on fire. Put the boiled egg on top. Negative
pressure will suck the egg into bottle. Then ask, “How do I get it out?” Take a
deep breath, create seal with your lips around the bottle, and blow. The
positive pressure inside the bottle will pop out the egg. Great way to
introduce students to the force of pressure.
5. The Floating Egg:
What will happen to the egg when
I put it in water? What will happen when I put it into water with salt? Egg
floats in salt water but sinks in pure water. Good way to teach introduce the
concept of density.
6. Pennies and water
displacement:
What will happen if I drop
pennies into these 2 full glasses of water? See how many pennies it takes to
make it overflow. First, perform with regular water. Then repeat with glass of
water containing detergent. It will take many fewer pennies to make the water
overflow due to reduced surface tension. Great way to introduce cohesion and
adhesion.
6.
Balloons and Air Pressure:
Insert
a deflated balloon into an empty soda bottle and stretch the mouth piece over
the mouth of the bottle. Blow air into the bottle. The balloon will not be able
to inflate because the air pressure inside the bottle is too high. Prepare a
second bottle and secretly poke a hole in the bottom. The balloon will be able
to inflate this time. Good way to introduce the concept of air pressure to
students.
7. Magnetic Cereal:
To teach students about magnetism
and iron in cereals. First, test whether cereal is magnetic by seeing if the
cereal is attracted to a magnet. Nothing will happen. Ask why. Ask students to
revise the experiment to test the magnetism in a better way. Guide them to
testing by floating the cereal on top of water in a petri dish. Now, the cereal
flakes will be attracted to the magnet. Ask why it worked this time. Guide
students to understand that floating the flake on water reduces friction
allowing the attractive force of the magnet to move the flake across the dish.
8. Which will hit the ground first?
This is a great way to introduces
students to the concepts of free fall, maximum acceleration, air resistance,
and mass. Start with a book and a piece of paper. The book will hit first due
to air resistance. Then crumple up the piece of paper. Now, both will hit at
the same time.
9. Which grape is heavier?
Start with a fresh bunch of
grapes. Peel one and leave the other untouched. Ask students which grape is
heavier and have them predict which one will float and which one will sink.
Students will most likely predict the unpeeled one will sink because it is
heavier. Put them into a glass of 7-Up. The CO2 bubbles can adhere to the
unpeeled grape, but not the peeled grape, causing it to float. The peeled grape
will sink. Good way to introduce students to concept of adhesive and cohesive
forces.
10. Mysterious milk:
Most students don’t
realize all the complex molecules that go into milk. This is a great way to
illustrate what colloidal properties are. It’s also a great way to introduce
students to chemical reactions. Take 500 ml of milk in a beaker, add heat and
vinegar. Watch the milk turn to a powdery paste. Milk contains fat and protein.
When milk is heated and acid (vinegar) is added, the protein (casein) denatures
and precipitates out of solution. The acid neutralizes the natural negative
charge of milk, causing casein to form micelles (small, hydrophobic clusters).
11. Crushing a soda can:
This a great way to
introduce students to the concept of temperature and pressure. Take a soda can
and place it into a container of water. Heat and boil the water with the soda
can in it. Then, immediately plunge the soda can into a container of cold
water. This causes the vapor to quickly condense, creating negative pressure
inside of the can. The can will be rapidly crushed.
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Design
Component
&
Criteria
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Approaching
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Meets
(Including the criteria for Approaching & Meets)
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Exceeds
(Including the criteria for Approaching, Meets &
Exceeds)
|
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Topic Title
0.5 point
|
Describes the strategies with
a topic title
Ex: Grouping
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& make sure the title
includes if the strategies fit under the preventive, supportive or corrective
approaches for instruction.
Ex: Grouping (Preventive)
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& a description of how the strategies fit under
the said approach.
Ex: Grouping (Preventive)
By proactively planning student work groups the
teacher can make sure that students are placed in groups that meet their
needs and as a result will help prevent problems and maximize student
learning.
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# of
Strategies
1.5 points
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1-9 Strategies are provided.
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10-20 strategies are provided.
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21 + Strategies are provided
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Strategy
Descriptions
1.5 points
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A brief description is
provided for most of the strategies.
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A rich description is for all strategies and
references are provided when appropriate.
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A rich description is
provided for all strategies and supportive materials are provided to model
the strategy.
Ex: Popsicle sticks with
student names
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Organization
0.5 point
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Strategy List is somewhat
organized, but could be more polished.
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Strategy List is well organized and easy to
comprehend.
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Strategy list is organized
in a way that is could be published for sale.
|
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Strategy
Variety
0.5 point
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There is some variety in the
strategies presented.
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There is rich variety in the strategies presented.
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There are more than 20
strategies categorized in subsets to emphasize the variety.
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Self-Evaluation
0.5 point
|
Provides a copy of the
rubric …
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& highlights the criteria for each component…
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& provides evidence for
each criteria marked.
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