Posted by David Wetzel
Greenhouse Effect
Greenhouse effect is the a current science event that discussed widely at all levels of education and beyond. Often students have a basic knowledge of the greenhouse effect; however, many just nod their heads and pretend they know and understand.
I have developed a simply experiment that gives students hands-on, minds-on experience with how the greenhouse effect works.
Greenhouse Experiment
Materials: 2 Thermometers and 1 Large Seal-able Plastic Bag
Procedures:
- Place one thermometer in the plastic bag and seal the bag.
- Record the beginning air temperature in the bag.
- Place the plastic bag in direct sunlight.
- Place the second thermometer next to the bag.
- Record the temperature of the second thermometer.
- Wait 15 minutes and record the temperature on both thermometers.
- Wait 15 more minutes and record the temperatures again.
Questions for Students:
- What observations did they make?
- What was the role of the plastic bag in this experiment?
- What did the thermometer inside the plastic bag measure?
- What was the cause of the temperature increase in the plastic bag?
- What was the effect of the temperature increase in the plastic bag?
- What could they do to lower the temperature of the air inside the plastic bag?
- How can they compare the effects of caused by the temperature increase inside the plastic bag, with the greenhouse effect the earth is undergoing now?
- Other questions will develop as the discussion continues.
Resources
Understanding Scientific Inquiry
Problem Solving and Science Process Skills
Questions to Ask Students in Science Projects
Greenhouse Effect Animation
Posted by David Wetzel
Rain Gauge
The primary moisture sources in the United States are the Atlantic and Pacific Oceans as well as the Gulf of Mexico. Winds around high- and low-pressure systems transport this moisture inland.
Once the moisture is in place, clouds still need to form. The most effective way for this to occur is for the air to be lifted. This is accomplished by forcing the air up and over mountains or, more commonly, by forcing air to rise near fronts and low-pressure areas.
Cloud droplets and ice crystals are too small and too light to fall to the ground as precipitation. So there must be processes through which cloud water, or ice, can grow large enough to fall as precipitation. One process is called the collision-and-coalescence or warm-rain process. In this process, collisions occur between cloud droplets of varying size, with their different fall speeds, sticking together or coalescing, forming larger drops.
Follow the instructions below to create your own rain gauge.
Materials
- Straight-sided glass or plastic container, with a diameter of about two inches or less (such as an olive jar)
- Coat hanger or wire bent to make a holding rack
- Measuring spoons: 1 teaspoon and 1/4 teaspoon
- Hammer and nails to secure the rack
- Felt tip marker
Procedure
- Rain gauges measure the amount of rainfall in cubic inches. So your first task is to make a scale for your container that shows how many cubic inches of water are in the container. One cubic inch of water is about 3 1/4 teaspoons, so you can draw the scale on your container by pouring 3 1/4 teaspoons of water into your container, then drawing a short line at the level of the water. If you look closely, the top of the water will seem to be slightly curved and thickened. Draw your line so that it matches the bottom of the curved surface (which is called a meniscus). This line corresponds to a rainfall of one inch.
- Add another 3 1/4 teaspoons of water to the container and draw another line. The second line corresponds to a rainfall of two inches.
- Repeat Step 2 until you have at least five marks on the container. This will be enough for most rain events, but you may want to add another line or two - just in case!
- Find a location for your rain gauge where there is nothing overhead (such as trees or a building roof) that could direct water into or away from your gauge. The edge of a fence away from buildings is often a good spot. Another possibility is to attach your rain gauge to a broomstick driven into the ground in an open area. Be sure to record rainfall soon after a rain event to avoid false readings caused by evaporation.
Posted by David Wetzel
When I was teaching one of my students’ favorite events in science was when they are challenged with discrepant events. So what is a discrepant event?
It is something that surprises, startles, puzzles, or astonishes students as they observe the event.
Often, a discrepant event is one that does not appear to follow basic “rules of nature” and the outcome is unexpected or contrary to what they predicted.
The event throws the students “off balance” intellectually, which typically motivates them to further investigate the science concept - minds-on.
Discrepant events promote problem-solving and critical thinking skills on part of the students. They are typically guided into finding a solution by the teacher, as they discover the reason for the discrepant event.
How I Used Discrepant Events
I would guide students to answers using open-ended questions, which caused my students to draw upon their prior knowledge and experiences (PKE).
I would begin a new unit or chapter with a discrepant event to stimulate their thinking processes, along with finding out what they already know. Then I would use a culmination event to reinforce science concept(s) studied and as post informal assessment. .
I would present some discrepant events as whole class demonstrations. However, my ultimate goals was to make them group investigations as much as possible.
How are Discrepant Events Used
Discrepant events can be used:
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To engage students in inquiry
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As a demonstration followed by discussion to introduce a new topic
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To engage students in science processes skills
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As a small group lab activity
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As a mind-on warm-up to stimulate critical thinking
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As a take home lab activity
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As a challenge for students to create investigative lab activities to find out more about the event
Additional Resources
Additional examples of discrepant event activities and procedures can be found by visiting:
Science Discrepant Events and Critical Thinking
Three More Discrepant Events in Science
