Paul Caginalp

Reflection paper

8^th grade unit

 

 

Day 1:  Day one went pretty much according to plan.  I started off by introducing Newton’s first law.  Many of the students already knew Newton’s first law, though I had to prompt them with “An object in motion…”  From there they could take it on their own.  I gave the law in three pieces in most of the classes.  I think it worked better in three pieces.  The students take an object at rest will stay at rest for granted.  That part is fairly easy to slip by.  They realize that anything pushing on the object will start it in motion and they realize that that is not playing fair.  The part they don’t take for granted is the object in motion.  It is their experience that an object in motion slows down and eventually stops.  It takes a little bit of effort to get them to see all the outside forces that are acting in a system of moving objects.  I wonder how many will revert back to their view that all objects eventually slow down.  I think that they understand that there are outside forces.  I tried to drill the outside forces pretty hard, both in getting a definition of outside forces and finding outside forces.  If I could have I would have liked to go back over forces.  I think that they have no clue what a force is.  They can recite that a force is a push or a pull, but they call things like inertia, or the floor forces.  If I could have broken them of that habit earlier then they would have had a much easier time with forces.  I used a Newton’s cradle a lot in the class to demonstrate where the outside forces were coming from.  I decided that my point of the day was going to be using the 1^st law with reference frames.  If they could have done it with reference frames, they could use it with anything.  I know I succeeded in confusing a lot of students, and maybe some came out with interesting questions.  I only got a really good discussion out of it in one class.  I still think that I would like them to be able to think of it in terms of reference frames.  I still believe that they can do it with regard to reference frames.  I wonder how I could teach it to them better.  I think that I would start out by asking if the stars are moving and try to build it from there rather than asking if the law works with reference frames.  The problem was with my starting question.  The idea is that it works as long as you remain in the same reference frame.  I think my demos for the day proved their point, and were definitely easy to do.  I only spent around 5 minutes on them because the students were so quick to tell me what was happening.  They understood right away that the moving objects were being acted on by outside forces.  If I ever do this unit again I will spend more time with inertia.  I defined inertia as the ability of an object to resist change.  I figured they could all relate to that since they all hate change.  It worked really well as a kid proof definition, but I just didn’t spend enough time with it for them to invoke it later.  They just needed more exposure and I didn’t provide it.  I will have to change the homework to ask for all the outside forces if I use it again .  At the time that I sent it to printing I was thinking that it was good because it had more than one right answer.  Thinking about it now, I think that it would have been more beneficial to them to see the whole picture.  Without doing free body diagrams (which I think should have been the beginning of the whole physics unit) they can’t ever see the whole diagram as well as they should be able to, but I think that they can see enough of it.  In this specific homework it could have been a great opportunity to see the whole picture, and instead they saw the first thing that might or might not have been a force and said “done!”  The day on the whole was a success, and I think that the homework reinforced what I wanted it to.  I think that they can relate outside forces into their bikes, cars, and themselves.  The only wonder I have is how strongly they will revert to the misconception that a moving object will eventually come to rest.  They need to remember that outside forces are everwhere.  Time for a quick note on the spotlight on a scientist activity:  I was only able to do one spotlight on a scientist for the four days I did the unit, but I think they enjoyed it.  They listened to the stories and generally laughed at them, which was the goal.  My goal for that activity is that the students could do it for themselves.  I would have had them do the spotlight on Pascal if we had gotten to it.  Not only do they learn a little bit about the scientist and get to learn funny stories, but I think it also shows them that they could do something great like that someday.  It breaks the idea that these guys are 100 times smarter than the kids will ever be.  I think it gives the kids a bit of confidence.

 

Day 2:  Day two was Newton’s 2^nd law.  This day I wish I had to do over again.  I started off by going over the homework.  To continue the review I had them do the first demo quick write.  The demo was that in a bag of water and air, a ping pong ball held to the bottom of the bag will stay at the bottom instead of rising to the top when dropped.  I certainly got their attention.  The answers of why it stayed at the bottom were horrendous.  I can’t say I expected differently.  I was looking more for the thought process, which most didn’t write down…they just gave the first answer that came to mind.  I think that these would get better with time.  I wonder if the demo was too hard for them to explain.  I probably should give more guidance with the first couple that they do like talking about what the demo is going to deal with.  I got mainly answers of gravity when I was looking for inertia.  I probably couldn’t have come up with the right answer unless I was prompted that it dealt with inertia.  Next time I will start off with what the answer deals with so they are thinking along those lines and then do the demo.  I was happy however that a couple of students were able to take the demo that we had just seen and apply it to what happens in a car with helium balloons when it slams on its breaks.  Up to this point I think the day was going fine.  At this point I made a fatal error, which was to introduce math into my plan.  I gave Newton’s second law as the equation f=ma.  In hindsight I should have given it in words. Words are easier to remember than a simple equation, and it makes the equation mean more.  The students were not able to remember Newton’s second law.  They could use the equation f=ma but it had no meaning and they couldn’t quote the equation as Newton’s second law.  Maybe giving the entire law in words, and then refining it down to the equation would have been the smarter idea.  In any case the students can use f=ma now, but don’t know why it is Newton’s second law.  From a test taking perspective it works, but knowledge of the whole law would be better.  The units of force also confused the students.  Even though I showed that one Newton is equal to a kgm/s².  I don’t think the students understand where the Newton came from.  I tried to explain it as physicists are lazy and would rather write an N rather than a  kgm/s² but units for these students are a tricky thing in any equation.  I think that the units of these things are too abstract for them.  I had a 1000g weight in the class.  If I could have showed that accelerating at exactly one m/s² and had the students feel that force, it might have made it better, but it wouldn’t have helped much for showing that a Newton is equal to the other measure.  The homework helped reinforce the law and use of the equation, however many of the students quoted the law wrong.  Some for whatever reason made it f=m/a.  I am not sure where this idea came from yet, so I have no idea how to combat it except to write the equation on the homework sheet for them so that they can’t possibly mess it up and it gets reinforced the right way.  General explicitness needs to increase on my part.  I found a lot of the students often didn’t understand what I was asking for.  I also need to work with them from the beginning of the year on how they set up problems.  They write the equation, but only some of them actively pick out or underline the numerical data that the problem gives.  They need to pick this out so they know what they can find and what they need to find.  I think that the second half of the day was just pretty much a wash.  It didn’t produce enough interest, and it didn’t get them to the point they needed to be at.

 

Day 3: This day was the day that Don came in to observe, it was also the worst of the four days.  The plan was to do a lab dealing with f=ma.  The day started with going over the homework which took longer in some classes than others.  Some I had to really correct from the day before, and others were much better.  After the homework I went straight to the lab.  I used the set up that they had done to find acceleration, and then went from there to get the force.  All classes realized fairly quickly that they would need a balance as new equipment from the last lab they did, and then proceeded to give me the materials and procedure from the last lab including the balance and massing of the frictionless puck.  The problems started when they didn’t know how the set up got them to an acceleration.  After doing the lab last time, and restarting it this time, I figured that the kids could handle a more complicated problem and I was wrong.  The main difficulty I had was that I had multiple distances and times in the data table that they ended up with, and they didn’t know the meaning of them.  I labeled them d₁, d₂ and so on.  The students had no idea what that meant.  I think that I went a little above their ability level with this.  If I had even changed the labels to d_near and d_far it would have helped a lot but I didn’t think of it at the time.  I did rearrange the data table by the end of the day so that it was easier for me to make connections, but I think the kids were so lost that it helped them very little.  A bit of attention to labels that day would have helped a lot, and it would have been easy to do.  I need to look at the small stuff more because it seems that the students get caught there a lot more than in the bigger ideas.  I ended up just cranking that part of the lab out to get past the confusion as fast as I could.  I think that if they had realized what parts of the lab gave them an acceleration, or if they had realized what the labels meant in the data table they might have gotten much more out of it.  The other problem was that I just wasn’t into it for whatever reason that day.  I was more into the lab in the morning, but it had drained out of me even by 3^rd mod when Don watched it.  It was just a throw away day on my part: I couldn’t control my own weather and it radiated to the kids.  I think that is why the classes were so dead silent that day. 

 

Day 4:  If you could have seen this day Don your impression for the second visit would have been far better.  I started by going over the lab and totally lost around half the students again.  By midday I was feeding answers to the lab and considering it a lost cause so I could get to Newton’s third law.  I think Newton’s third law was a complete success.  I started off by asking how a space shuttle gets off the ground.  The first time I asked it I asked how a space shuttle moves, but quickly learned that the answer to that was thrust.  The question of getting off the ground got me to where I wanted to be.  Another case of asking the right question.  The students responded after a little prodding that the shuttles release gases which push on the ground and make the shuttle lift into the air.  I kept moving the shuttle till it finally got into outer space and it had nothing to push on, and finally stumped the students as to how it moves.  To get to why they move I had the students bring in skateboards.  The skateboards provided a lot of excitement in most of the classes, and in some a little more rowdiness than I would have liked, but they demonstrated the points well.  I had 2 students push off of each other, and asked why they moved backwards.  The students responded that they transferred the push to each other and hence moved in the direction they were pushed.  Next I had the students push off of my stationary arms to demonstrate that they could push inward and they would still move backwards.  I was looking for the idea that they pushed on my arms, and my arms pushed on them but I rarely got it.  I let it go without an answer until the discussion died down, and proceeded to the third part of the demonstration.  I loaded down my bag with texts and other weights (good use of texts teehee) and asked a student on a skateboard to throw it to me.  The throw produced the desired result of the student moving backward noticeably pretty often.  Some didn’t appear to move much, but you could tell that they had some small force backwards.  I let the discussion from there move in various directions, but finally brought it back to get Newton’s third law.  Some students knew what I was getting at right away, and other classes took longer to get there but eventually they all arrived.  I took the law and applied it to the space shuttle example of before, and in each class the students were able to take it and apply it easily.  I tried to keep their interest by showing them how to abuse the 3^rd law.  I picked a student in each class and gave them a little shove in the shoulder, and then accused them of pushing me.  Most of the students caught on fairly quickly and thought it was hilarious.  In some classes the joke went a little too far and I had to calm the students down before continuing, though most of them took to the application well.  I was especially proud of my little bit of social commentary that if someone punches you then you need not punch them back since you have already hit them back with the exact same amount of force that they hit you with.  Most of the students were able to point out that they would rather have applied that force with their hands rather than with their nose but understood that they had already hit back.  I decided to push their use of the law and give a little bit of a preview of pressure by moving into an example of hunting.  The students were able to establish that the force on a bullet would be high, and that the same force should come back into your shoulder.  I then put forth my idea for better hunting.  You walk up to the deer and fire the gun.  The deer fires off into the woods.  The bullet goes off harmlessly, the deer catches the kick back and dies, and my shoulder doesn’t hurt.  Most of the students laughed and acknowledged that it wouldn’t work for reasons other than the deer can’t fire guns.  I got to a discussion of even though the students didn’t recognize that they were talking about pressure, and I let the discussion go as long as it needed to.  The major regret I have from this lesson is that the misconception was not fully broken in most students that the action doesn’t need something to push on for the reaction to happen.  I was shown this in my 7^th mod class by one of my students who kept asking questions about it.  The students were working on CO₂ cars in Tech class (had I known this it could have been an interdisciplinary project) and the student asked whether or not the car would go faster if placed near a wall to start or not.  I tried to get him to acknowledge that it wouldn’t since the reaction doesn’t need the action to press on anything.  I eventually acknowledged that the car would go faster because the air coming out of the CO₂ canister bounces off the wall and gives a little bit of beneficial wind to the movement of the car, but I don’t think I should have.  I think I should have left it at no, the car will not go faster.  Had I done that I would have had a better chance of breaking the misconception.  I need to plan out a way to break that misconception earlier.  The student throwing a backpack from the skateboard works well, since there is nothing to throw it against, and they don’t generally think of air resistance being a factor in that example.  If only they would apply that logic all the time.  Just hammering at the misconception as I did in 7^th mod didn’t seem to work at all, so I need something to break it other than lecturing on it.  I wonder if more examples like the bookbag/skateboard example would break it because otherwise I have no clue how to do it.  The demo quick write (a balloon propelling itself when let go) went well but also showed that some of them held on to the misconception and stated that the air flowing out pressed on the air that was already in the room.  I shot those theories down as fast and as hard as I could, but I am not sure that it helped any.  Many students got the answer right, and a few even went so far as to say that the balloon was pressing inward on the air to expel it since the air inside would much rather stay at rest.  On the homework I reinforced the 3^rd law as well as the 2^nd law a little bit and saw a vast improvement since the day before on the 2^nd law, but they had a much firmer hold already on the 3^rd law. 

           

A few quick notes that didn’t fit anywhere else:  First off my lessons were gender biased.  I picked examples that catered to the prior knowledge that boys would have.  While one of my girls did bring in a skateboard, and many more had shot guns that I would have originally thought it still was a boy centered lesson.  I need to find more examples that apply to girls, but I know the ones that apply to boys much better.  I suppose that gender neutrality will come with experience but right now it is bugging me.  Something else I should note is that I need to work on my classroom management skills a lot.  The classes that I took earlier on were much less disciplined than the ones I took later.  I take that as a sign that I am improving but I still see a lot of room for improvement.  I view it as a miracle that Don saw two relatively calm classes.  I think that some classes got out of hand to the point that it was disturbing students learning.  I tried to bring those back quickly, but I know I lost time in there.  Other classes I had students that I didn’t bring back on task even though I knew they were off.  Bill’s philosophy plays out as if a student is disturbing their own learning but not others then he lets it slide, and I took part in it while I was in his classroom but I don’t think it is a particularly good philosophy to hold.  I don’t see it as a worthwhile task to ram information down students throats, but I also don’t know what to do when I have a dry lesson every once in a while.  I don’t want the students to expect a high energy fun lesson every day, because then they will disengage easily when there isn’t one.  I guess that’s just something I will have to continue to work on.  Lastly I think that the unit needed to be split up differently.  Going through Newton’s laws looks good until you realize that the second one really has no relation to the first or third.  The first and third can be put together fairly easily by looking at any object, and identifying the outside forces, and then out of those picking the action and the reaction.  For the second to incorporate you need to know how fast something happens and the objects mass.  It can be linked into the third law much easier than the first.  Doing the laws in the order of 1, 3, 2 seems much more rational to me now.  This may screw up the idea of going into pressure with the hunting example in the third law, but you can always do it as a math problem at the end of the second.