HEAT EXPERIMENT#2
Start and end each session with a visible thinking learning task - what I used to think and what I think now - to help implement the Five Formative Assessment Strategies to improve student learning.
Why we focus on 'understanding the principles' rather than on 'learning the facts'
- If your teaching/learning focuses on an understanding of the principles, you don't need to remember the facts - just look them up. No matter how many facts you remember, there is no guarantee that you will ever understand the principles that underly them.
- All that you need to understand about the current scientific view about heat is….
“The beauty of a living thing is not the atoms that go into it, but the way those atoms are put together” 1)
Everything in the universe is made up of matter and energy.
- Matter is made up of atoms and molecules (groupings of atoms).
- Energy causes the atoms and molecules to always be in motion - either bumping into each other or vibrating back and forth.
- The motion of atoms and molecules creates a form of energy called heat or thermal energy which is present in all matter. Even in the coldest voids of space, matter still has a very small but still measurable amount of heat energy.
- Energy can take on many forms and can change from one form to another.
In summary, put energy into a system and it heats up, take energy away and it cools.
- Heat can be a chemical or physical phenomena but all chemical phenomena ultimately reduce to physical phenomena (physics)
- Thermal energy itself can cause a substance to heat up, simply by increasing the speed of its molecules. For example, when we are cold, we can jump up and down to get warmer. If we stop moving, we cool down. 2)
Video: Veritasium - States of Matter (4min)
- IF UNABLE TO ACCESS YOUTUBE VIDEO, TRY:Viewpure
The five important concepts about heat & temperature
- Temperature - A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale.
- Conduction
- Radiation
- Convection
More detailed information about the following videos can be found in the Teacher Workshops section of this WIKI:
Conduction experiment
- Place a metal spoon and a plastic spoon into your container. The handles should be inside, and tops outside.
- Fix a plastic bead to the top (outside part) of each spoon with a dab of butter
- Your teacher will pour some hot water into the container
- What is your hypothesis?
Video 1 - Eureka - Conduction (2min)
- IF UNABLE TO ACCESS YOUTUBE, TRY:Viewpure
Radiation experiment:
When any type of light is absorbed by an object, that object will be heated. The infrared light from an electric heater feels hot for two reasons: 3)
- Use an infra-red light source to heat up an object
- Use a mobile phone or infra-red camera to view a TVV remote control unit when pressing buttons
- View an ice-block in infrared.
- because surfaces seem black to infrared (IR) light, IR light is absorbed by objects.
- because the infrared light (IR) is extremely bright light (although we do not see it).
A thermographic camera (also called an infrared camera or thermal imaging camera) is a device that forms an image using infrared radiation compared with a standard webcam/camera, which forms an image using visible light.
Figure 1. Thermographic Images - Show how a ball heats up after being bounced - Source: Caltech
You may think these infrared images of a boy holding a ball look unusual, but this is the way snakes normally see things!
Video 2. Eureka - Radiation & waves (4min)
- IF UNABLE TO ACCESS YOUTUBE, TRY:Viewpure
Convection Experiment
- Place a clear container onto some paper cups
- Place red food dye in centre, blue food dye at each end
- Place a cup of hot water under the centre (below red food dye)
- What is you hypothesis?
- What happens
- If warm air rises, why is it always colder at the tops of mountains? Does hot air really go up (bouyancy)?
Video 3. Eureka - Convection (5min)
- IF UNABLE TO ACCESS YOUTUBE VIDEO, TRY:Viewpure
Video: GCE Physics - Heat Transfer by Convection (4min)
- IF UNABLE TO ACCESS YOUTUBE VIDEO, TRY:Viewpure
Video: Convection - Science Demonstration (3min)
- IF UNABLE TO ACCESS YOUTUBE VIDEO, TRY:Viewpure
Video - Fire, Heat, Light & Hot Air Rising (1.5min)
- IF UNABLE TO ACCESS YOUTUBE, TRY:Viewpure
- Hot Air, Bouyancy, Balloons (Smarter Every Day)
A QUESTION - Does 'heat rise' and/or 'does hot air rise'?
- 'Does hot air rise (due to heat)' or does 'cold air fall (due to gravity)'?
- When you have two theories to explain the same thing, what can you do
- To test a theory, design an experiment where each theory predicts a different outcome.
- In the space station, there is plenty of air but almost no gravity.
- If hot air rises, then it should also 'rise' in zero gravity. Does it?
- High above our planet in the realm of satellites and space stations, the familiar rules of Earth do not apply. The midday sky is as black as night. There is no up and no down. Dropped objects do not fall, and hot air does not rise.4). In the absence of gravity, there is no buoyant force so no movement is possible physically but however hot air will start exchanging heat with the cooler air by means of conduction and radiation if they are in contact with each other and only by pure radiation if they are not in contact. ( no convection can takes place because of the absence of gravity) 5)
BEFORE END OF SESSION (allow 10 minutes)
Learning Tasks That Elicit Evidence of Learning 6)
At the end of this session, write down new answers to the same two questions you answered earlier:
- Are 'heat' and 'temperature' just different ways of saying the same thing?
- How does heat move from one object to another?
Have you changed your mind about any of the answers you gave at the beginning of the session?
References
1)
Carl Sagan - https://www.youtube.com/watch?v=XGK84Poeynk
2)
Jiggling molecules - http://coolcosmos.ipac.caltech.edu/cosmic_classroom/light_lessons/thermal/heat.html
6)
Dylan William - Formative assessment https://www.nwea.org/blog/2012/dylan-wiliam-the-5-formative-assessment-strategies-to-improve-student-learning/