Physics 4810 7810 Week 5 Learnin Day 10 Fa2008 Knowledge in Pieces Application to Newton Dynamics and N3 Redish Jigsaw 1 What are our goals for physics instruction 2 What is social learning Does it include lecture Does technology affect it 3 How can we teach students how to use multiple representations and pick out the significant pieces of information from a problem 4 How do these theories of memory apply to teaching and learning 5 What s better bridging or cognitive conflict What are their advantages disadvantages How would we implement bridging in tutorials diSesssa Jigsaw 1 2 3 4 5 Can you think of possible p prims you have used or encountered Have you ever had your p prims challenged by instruction and learned as a result Is physics simply a way of reorganizing clarifying and expressing p prims DiSessa notes a number of differences between p prims and logic Do you agree with his contrasts between the two Are p prims not logical How does the second section of the paper on dinosaur cartoons relate to the first Why are these two sections in the same chapter Has anyone experienced one of diSessa s rare events that sparked your interest in physics in particular and science in general Has anyone not experienced one of these events If not what got you interested in math and science Jigsaw Approach i Form groups of disciplinary expertise ii Jigsaw regroup into distributed expertise in order to solve broader problem Broad Question from Redish Broad Question 1 We ve seen evidence that Tutorials are very effective at teaching physics concepts Why b Is it because they re well written Is it because they encourage social learning Is it the extra time spent a Should we scrap lectures and focus on tutorials Is it too expensive Will it just be the blind leading the blind and therefore produce improper learning What about unsocial students Broad Question from diSessa Broad Question 2 How do you make use of p prims and rare events in the classroom 1 September 10 2001 DiSessa What is the relationship between a p prim and a conception Is conception some sort of higherlevel knowledge than a p prim i e is it made out of them I would like to learn more about these p prims and look into regorous studies on their properties and how we develop them Doing Science Tools for Building Knowledge Science is a process that studies the world by Limiting the focus to a specific topic making a choice Observing making a measurement Refining Intuitions making sense Extending seeking implications Demanding consistency making it fit Community evaluation and critique Making a Measurement and sense We think we see the world around us but How do we know we see things the same reliable How do we know that we see things correctly Physics 121 Prof E F Redish Theme Music David Hildebrand The Motion Detector Rag Cartoon Gary Larson The Far Side Making a choice Chosing a chanel on cat television Relates to the questions we are asking Making a measurement Do these line segments look the same Are they valid Our own VR We gather info through our senses Our brains interpret these stimulae But don t necessarily get them right 2 Making Sense What is this Hint it s an animal Hint it s not oriented correctly Making sense of physics Does this look like dots Or deep relations of electric forces Hmmmm Does this help Seeking Implications Elaboration when we assume one thing it is bound to have implications beyond the exact case we are considering Figuring out what something implies is a good way to examine the thing itself And develop MODELS which are applicable beyond our immediate case Seeking consistency Making a Fit Science seeks consistency in patterns Want our principles to be as broad as possible Breadth depends upon the state of what we know Physics has been around for quite some time and hence developed a high degree of consistency 3 The puzzle analogy Next steps summary cues Seek consistency Patterns fit Lack of consistency leads to frustration The same is true in physics Making a choice Making a measurement Making sense Elaboration Coherence September 28 2001 Physics 121 Prof E F Redish Outline Theme Music Indigo Girls Galileo Cartoon Pat Brady Rose is Rose Implications If that s true then Example A r f table A r N B A B r N table B r f table B r N table A B A r N hand A r Wearth A Recap of Free Body Diagrams Working out the implications Newton s 3rd Law Reviewing Newton s Laws r N A B r Wearth B Consider the example above If we assume no friction how does the pair of blocks speed up Consider them first as a single system The problem is much simpler then Afterwards lets consider it as two separate blocks What does the result of treating it as a single system tell us 4 Now consider each box separately A r N table A B r N hand A B A B r Wearth A B Compare the equations All the accelerations must be the same r r mA mB a N hand A r mA a r mB a r r N hand A N B A r N A B r r r r mA mB a N hand A N B A N A B Newton s 3rd Law When two objects touch each other each exerts a force on the other Forces are interactions between objects In order for our analysis to be consistent when two objects interact the forces they exert on each must be equal and opposite This must be tested experimentally Strangely enough it works r r FA B FB A r N table B r N table A r N B A r r mA B a A B N hand A B B A B r Wearth B r N hand A r Wearth A r r r m A a A N hand A N B A r N A B r r m B a B N A B A serious implication In order for our treatment of the two objects as a system and as separate parts to be the same we must conclude r r N B A N A B 0 or r r N B A N A B Does N3 always hold We were able to check N3 for a lot of cases of normal forces in tutorial last week and it always worked Test it For tension and friction forces we could also do the experiment and see that it works For gravity and electricity and magnetism things are a bit more subtle We can t really measure the effect of small objects pulling up on the earth but they could be there 5