# Day 149: Aspire Testing ….

The Aspire 10 Test… were do I begin to write about this???? I know, I start by giving our administration, or IT crew, and our students, and I can’t forget my colleagues that proctored the tests today a HUGE SHOUT OUT. They all really deserve it because we had some pretty major technical issues that they handled with amazing patience during the first test.  Imagine about 1000 kids working on tests on issued Chromebooks…. see why they deserve this shout out.  They had things running really smoothly for the next two tests, so much so that I’m not the least bit concerned about round two that takes place tomorrow… really, not concerned.at.all.

One cool thing about our Aspire schedule is that I only had 3 of my five classes, well that’s not the cool part.  The cool part is that each class was a full hour-long vs. our normal 53 minutes.  Yeah, I know only 7 minutes, but 7 minutes is seven minutes. Tomorrow I get the other two for 65 minutes.. awe yeaaaaaahhhhhh.

We started the hour by taking an assessment on Coulomb’s Law.  Here are the two problems I allowed the students to choose from:

The next installment of the Mr. Wunderlich questions.

This one was edited just a bit from Jones and Childers.

We also had time to start the discussion the develops the concept of the electric field.  I start by explaining the we still do not have a name for the slope of our Fel vs. Charge on q2 graph from our Coulomb’s Law experiment.  So I just retrace what we do know about the slope (it increases with a bigger q1, and decreases with a bigger ‘d’) We then review how we ended up with Coulomb’s Law:  Fel=(kq1q2)/d^2…. and that this is a long-range force.  I remind them that we have  only looked at one other long range force, the gravitational force.  I confess that I did not provide ALL the details at the time we developed our model for the gravitational force.

SIDEBAR: This was from our Fg vs m experiment  where the slope equals ‘g’ defined as the gravitational field strength for the earth, with the model being Fg=gm.

I explain that the REAL equation for the gravitational force is called The Universal Law of Gravitation… Fg=(Gm1m2)/d^2.  This is how I get to the Universal Law of Gravitation.  We stay on the earth so the equation o: Fg= (G* mass of the earth* m2)/(radius of the earth)^2.  We play with a few calcs. where I MAKE them use the entire equation over and over and maybe over until someone complains.  Then we do another calculation:  (G*mass of the earth)/radius of the earth and … boom it equal 9.8N/kg.

Now it is an easy transition to Electric field (for point charge like we had in our experiment) =(kq1)/d^2.  This is our unknown slope.

I like this progression.  It explains why we get 9.8N/kg in the ‘Fg’ lab; why different planets have different gravitational field strengths; an introduction to the idea of a field.  I suppose I could introduce it right away when we do the Fg lab and then maybe the student might recognize the slope of the Fel vs charge graph right away…. hummmmm, I’ll have to write that down for next year.

From here I head into a uniform electric field created by a positive plate and a negative plate to build the concept of electric potential and electric potential difference (slang term = voltage), a Leyden jar, a capacitor and an electrochemical cell.  It is a difficult set of days for the students and for me… usually it is most me talking/telling.  I just feel that an advanced physics kid that may go on to take more physics needs to be exposed to the electric field and electric potential  (instead of just being told voltage is….).  I really do not have the strongest background in electrical concepts which why it is also difficult for me.

Unfortunately, this year, the entire discussion gets (even more) glossed over because if I we don’t there will not be much  w time left for circuits, a topic that ALL our kids ‘use’ on a daily basis.

General Physics — Did not meet today because of the Aspire Test

# Day 148: Coulomb’s Law and The Biggest Horse

We finished WB’ing the Coulomb’s Law Practice problems.  I really like this problem:

because it provides a chance to ask a few really nice follow-up questions.  For example, (once the two forces are drawn in), sketch the net electrostatic force (a nice chance to quickly  review adding vectors tip-to-tail).  Another follow up is to ask for the position of the little charge +q (assuming A and B are anchored) an instant later…. then another instant later.  The majority of students think the +q follows the net force line…. forgetting that now the two individual electrostatic forces are now different meaning another different net force.  I think it provides a really nice preview for electric fields, where we are headed next.

We also discussed the Charge assessment they took yesterday.

General Physics:

We purple penned the work(ing) problems they solved in small groups yesterday.  After this, we predicted one more graph from what we did yesterday… the Work(ing) as a function of time.  You fully realize that it is linear:

and that the slope of this graph is the energy transferred each 1.0 second… or power.  We wrote the EOL that, when rearranged, gives the usual power equation.  We talked about the different units for power, watts ft.lbs/s and of course horse power.  We even converted the slope for the student into horsepower… quite a few laughs about how small it is… the perfect segue into  the activity called the Biggest Horse.  This is just a simple activity that we use to have the students practice working, and power calculation by determining their power output.  Here a clip of two students doing the simple activity:

It uses old 10 pound weights.  I’d really love to find a set of 5 lb weights to give the students the chance to debate lower mass (force) in a shorter time or big mass and possibly slower time.  We enter all the data into a spreadsheet to check the calculations and to rank the students.  The Biggest Horses (make and female) in each class are given a prize… a Power Bar !!

# Day 147: Charge Assessment and Work(ing)

Well it is the Monday after prom… ’nuff said’ right?  No surprise that most of my students became more sluggish as the day progressed.  So here is what we did.

The Advanced course took a ‘Charge Processes’ assessment.  I’m trying something new this year … rather than a summative test on charge; Coulomb’s Law, Electric fields and Electric Potential, I’m going to go with a few short assessments and skip the nitty gritty on how we transition from electric fields to electric potential.

SIDEBAR:  Part of the decision to do this is based on how far ‘behind’ I am from previous years.  We have lost sooooo may days for this, that and the mandated testing, that I am scrambling a bit to cover what I usually do.

Here is the assessment they took today.

Essentially it is straight out of Arons.  I really like it.  After the assessment, I allowed them to work in small groups to finish a practice set on Coulomb’s Law and then prep a WB for tomorrow.

General Physics:

Today we developed the model for work(ing).  I followed the same basic discussion approach I did with the advanced students I wrote about here.  The only real difference is that we do not talk about power right away.  It has been my experience that even though power is not a very difficult concept, sometimes piggy-backing the two concepts leads to confusion for these students.

# Day 146: It was a ‘Diverse’ day

For the last bunch of years (at least 10) one of our clubs (The Heart Group) has sponsored and planned a Diversity Fair. It is an impressive undertaking planned by this group of students to celebrate and promote our diversity.  The fair officially kicks off with an assembly that sets the tone for the day.  This year, the focal piece was a student created video about labels and being human.  I am continually impressed with the work that some high schools students can produce.  The rest of the day, classes still run, but so does the Diversity Fair complete with workshops and booths.  Teachers can opt to take their entire class to the fair if they wish to.  Because of the assembly, our classes were shortened to about 40 minutes.

We finished the Coulomb’s Law experiment but sharing the slope values for the final graph.  The post lab discussion was this part was very easy because when the students wrote the EOL for the graph, Coulomb’s Law is what they write!  After this, we looked at an easy sample problem.  It took a bit to convince them NOT to put the sign on the charge into the equation.  I explained that this sign is NOT a direction like our other (+) and (-).  Any time left was spent working in smalls groups on a set of Coulomb’s Law practice problems.

General Physics:

Today was just spent completing the questions for the Racquetball leaper.  Again a nice plan because it allows the students to ask for help as needed.

# Day 144: Electric Force (Paradigm) Lab and “Ba Bam!!!”

Today we whiteboarded the last question on the charge practice sheet.  Here is it:

It is chance to have the students confronted with another N3L question.  Most of the students saw that is the electric force exerted on A, by B was the same size as the electric force exerted on B, by A.

It also provides the perfect introduction to an electric force experiment.  I simply ask what the students think the magnitude of the electric force depends on.  They quickly suggest the amount of charge on each balloon, and the distance separating the two objects.  And… right there is the purpose of the experiment… determine the relationship between the electrostatic force and the charge on each object and the relationship between the electrostatic force and the distance separating the two objects.

We use a simulation to gather the data because, well, because it is MUCH easier than trying to really get accurate and quantifiable data. Here is the handout Electrical Force Simulation(13-14)I give the students, it includes a screen shot the simulation screen.  Here is a link to where I found the simulation last year.  I like this one because it does not give too much away and allows a variety of charges and distances.  Tomorrow we WB the results. and develop Coulomb’s Law.

General Physics:

Today we finished the How Hot Are Your Hot Wheels activity; I told the students at what point I wanted them to predict the velocity of the car, so where I would place the photogate.  If you read yesterday’s post, I was concerned about getting accurate velocity data needed in order to determine the dissipated energy and the frictional force.  Well here is screenshot of a group that used a Vernier Photogate to gather the data and to predict and check the velocity.

That’s what we call a “Ba Bam”… nailed it.  Here is a screen shot of a group that used the BeeSpy photogate for the entire experiment:

And again, another Ba BAM!

Moral of the story, if the students are careful when gathering the data, the results are awesome.  Seriously, how awesome are those results??  Pretty ‘darn’ awesome.  PHYSICS ROCKS!

SIDEBAR —> I still have to collect some from each class, and I’m pretty sure there will be a few that are not that close.

# Day 143: Da Da Da Dut da daaa— Charge! and Not so Hot Wheels

As explained yesterday, today was about practicing with the charge model. We were still WB’ing the practice sheet, but that went hand-in-hand with drawing a series of pictures for conduction and induction, and each student having an opportunity to charge an electroscope with each method:

General Physics:

Well, I really like the Hot Wheels activity for energy conservation… after all, who does not love to play with the little cars?  The issue for some today was that the kinetic energy at the bottom of the ramp, had a greater value than the gravitational energy at the op of ramp… not so Hot.  So is the error with the determination of the change in height or the velocity?

I think I figured out the issue.  I was using  a single photo gate with ‘One Gate Timing’ to get the instantaneous velocity of the car at the final height.  I’ve used a single photo gate successfully over and over and over and over …. it’s one of my favorite uses of the photogate. When I run the experiment, no issues, but when some of my generals did it, they must have measured the ‘flag’ incorrectly.  It is a narrow flag to give a better value for the instantaneous velocity, but even a millimeter off makes a difference when the energy values are so small to start with.  Tomorrow I will try a different photogate, one with no flag needed… a Bee-Spy photogate.  I am pretty sure the cars will fit through.  Stay tuned…

# Day 142: How Hot Are Your Hot Wheels?

The class did two things today, well, I did one and the class did the other.  We discussed the conceptual part of their summative impulse and momentum test.  All of my tests have two components; a conceptual part which is mostly multiple choice (at a higher DOK than simple recall) and a problem set.  The conceptual part is usually about 10 or 15 MC and there are usually one or two problems depending in how many objectives being assessed.  On this recent test, there was an impulse problem and a conservation of momentum problem.  On each test I also provide an opportunity for the students to really challenge themselves by providing a choice of two problems that both address the same objective.  For example, on this recent test the student could choose to do a pretty standard run-of-the-mill explosion problem or a ballistic pendulum problem.

This time we did not discuss the problems.  Rather, I am going to have the students make corrections on the problem(s) they will re-assess in addition to some posted practice problems.

After discussing the multiple choice component we moved to WB’ing the practice sheet putting all the components of the charge model together. We really did not get so far, only through the series of pictures to explain charging by conduction. We will finish it tomorrow.

General Physics:

We had a practice COE assessment and the started a COE activity that has two parts.  The activity is based on this problem from the assigned practice:

The basic premise is whether or not 10% dissipated is a realistic value.  To test it, we are using Hot Wheels and track to recreate the problem.  Essentially, they will solve for the Energy dissipated by taking the difference between the initial gravitational energy and the final kinetic energy.  The velocity is measured at the bottom of the track/ramp with a photogate.

The follow-up will be to have the students use the values from this part of the activity to predict the velocity of the car at some spot along the ramp that I place the photogate.

# Day 141: Harry Potter Visits NHS (or an intro to electrostatics)

Yeah, I know it is a pretty big jump…. from the momentum model (including impulse) to electrostatics. I’ve never been really pleased, but have never taken the jump to put momentum in somewhere else.  I guess just more to ponder.  Anyway, today we white-boarded ‘The 7 Charge Questions’.  It is a worksheet I out together to build the essential aspects of charge. It’s nothing fancy mind you.  It just gets across the info I want the students to understand about charge (symbol,units), how objects get charged (friction, conduction, induction), how objects get uncharged (grounding), that there are only 2 types of charge (+ and -), how charged objects interact (likes repel, opposites attract, and that implies a force is exerted between the objects, that charge is mobile and can be transferred (both + and -), oh yeah, and what polarization is.  All of this helps us form a model of what and how it behaves.

It’s interesting that many students just want to define charge as being when thee are more or less electrons.  But then I ask them what an electron is.  They politely regurgitate ‘a negatively charged particle’.  But wait… charge is when there is more or less charged particles?  Then they see there is a bit more to it.

After discussing for a while, we finally do a demonstration to bring many of the aspects of the charge model together:

What you do not see is the way I introduced it… I did the demo first, dressed with Harry Potter glasses and a cape.  The Harry Potter Halloween theme was playing on repeat the entire time.

VIDEO DISCLAIMER: The young lady in the last clip is from two years ago.. it’s just a nice longer clip and she is an awesome daughter (err, I mean  student).

For the next class, the students were given a practice sheet. Again, nothing too incredible, but they do have to draw a series (at least three) diagrams to illustrate the process of induction and the process of conduction.  In the next class meeting, they will also have an opportunity to demonstrate mastery by charging an electroscope using induction or conduction.

General Physics:

This class period was spent white-boarding a series of COE problems.  I also used it as an opportunity to do two things. (1) Ask some conceptual questions about the given situation (if the mass had been twice as large…), and (2) show them the power of substituting equations FIRST before putting values in.  For example:

In this case, Eelas = Eg.  So rather than solving for elastic energy, then setting it equal to the gravitational, then using that value to solve for the height., simply substitute in the equations:  1/2kΔx^2 = mgh, now solve for h.  Using this approach makes it soooooo much easier to answer the conceptual questions like what is the mass had been twice as large….

# Day140: No school for me today .

Yep,I was not at school today. I was at UW-O attending a CAPP workshop.  I really dislike being gone from school.  I just don’t like it.  I don’t like writing sub plans, even though the usual subs in our department are awesome and they have science backgrounds. I was not so fortunate today… more on that later. I don’t like worrying if my students are doing ok with what I left them.  I know I don’t have to worry, my kids are awesome and work really hard.

The best part of my day was getting to spend 3 hours talking physics and pedagogy with 8 other CAPP Physics teachers and our UWO Physics liaisons.  Truth be told, I did really get anything out the rest of the workshop… which brings me back to  I hate missing school.

So what did we talk about? We discussed grading practices… high school vs. college; re-assessments, topics to be taught and sequence. We had a few ideas shared. Some of the instructors were not aware of Direct Measurement Videos… they are now!  We also saw a great presentation on Dark Energy and Dark Matter… I have sooo much to learn.

So what did my classes do while I was away.