The non-textbook reading I shared with classes for a different perspective may be seen here
Today, labs were turned in, we looked at the forecast and it appears our barometer will measure some high pressure while we're gone rather than here this weekend. :(
I answered questions on the lab that you were supposed to guess on: can water/ice get colder than 0 degrees C? Yes. As a matter of fact the ice you worked with in class was much colder. Just at the surface, we see water and melting ice at 0C.
Can water vapor get hotter than 100C? Yes. Your teachers next year will surely do a demonstration with superheated water vapor/steam, or you can look up some cool stuff on youtube.
Where do the bubbles form in boiling water, and what are they? They should appear at the bottom of the container as long as it's being heated from the bottom (smart if it's following convection rules)... and the bubbles are Water Vapor - that explains where they come from - water expands and jumps to the gas stage, which is much less dense, and moves to the top of the water as a bubble.
We looked at the graphs of heating water and identified that most people's graphs showed little change in temperature of the ice/water until the ice melted, and little change in temperature while boiling. That's because when phase changes are occurring, any energy transfer is going into changing the phase of the water, not into changing the water's temperature. It takes a great amount of energy to change phase.
Two definitions: Heat of fusion: the amt. of E required to freeze/melt water
Heat of vaporization: Amt of E required to vaporize/condense water. (note - this may happen at temperatures other than boiling point! - ex. you when you get out of the shower, etc.)
Latent heat: E stored/released (hidden) in liquid/solid/gas states of water - released and absorbed in phase changes. Latent heat is not detectable by a thermometer alone; the total energy content of air is well connected to its humidity.
On Monday, we'll have some problems to help guide your review. I have listened to suggestions and we will have harder review questions that are involving transfer to unique situations and will challenge you as much as or more than the exam will. Tuesday we'll take a departure (from weather) and deal with one facet of global climate: energy efficiency - why/why not and how you can make a difference for your pocketbook and our resources. (goes along with the optional assignment I posted yesterday)
Wednesday we'll have a QUEST on meteorology: smaller than a test, bigger than a quiz.
Friday, March 30, 2012
Thursday, March 29, 2012
Lab, new optional assign, Exam next Wed.
I haven't finished scanning the review pages; hopefully those will appear online here tomorrow before school is out.
Wednesday we had a lab involving phase changes of water - and a couple of side labs too - melting ice with pressure rather than thermal energy (since water is a rare substance where its solid form is less dense than the liquid form), and melting ice with salt - again, no thermal energy added by the salt, but a change of the ice's melting point and the temperature at the outside of the ice cube, being lowered, increases the rate of thermal energy absorption for the ice cube AND keeps the water liquid at temperatures well below its usual melting/freezing point.
Labs are due tomorrow (Friday) and have been homework/classwork for this week.
Today classes got to see a barometer, watch the forecast (we'll see how the barometer reacts tomorrow as the Low pressure cell is supposed to move in before the weekend's High), read through a packet of review material (will be online ASAP for you to review), and we discussed observations from yesterday's lab along with any questions about the lab, graph, or post-lab questions.
Tomorrow we'll hopefully have a couple of new demonstrations (I haven't done them before) and I will try to address some of the questions on the lab that you were asked to make educated guesses about. We'll also have some notes on phase changes and try to use data from your lab to support the ideas discussed. Homework will be review problems; they will be posted online tomorrow.
I have been asked by several folks to put up a new optional assignment, and the one I was hoping to use for meteorology isn't going to work. Here's an alternate - there are two different pages you'll need.
worksheet
scoring guide
I'll try to give you some good ideas for this in class early next week, and put a list up online of some good ideas to help you out. Due date for this is Friday, April 13th.
Wednesday we had a lab involving phase changes of water - and a couple of side labs too - melting ice with pressure rather than thermal energy (since water is a rare substance where its solid form is less dense than the liquid form), and melting ice with salt - again, no thermal energy added by the salt, but a change of the ice's melting point and the temperature at the outside of the ice cube, being lowered, increases the rate of thermal energy absorption for the ice cube AND keeps the water liquid at temperatures well below its usual melting/freezing point.
Labs are due tomorrow (Friday) and have been homework/classwork for this week.
Today classes got to see a barometer, watch the forecast (we'll see how the barometer reacts tomorrow as the Low pressure cell is supposed to move in before the weekend's High), read through a packet of review material (will be online ASAP for you to review), and we discussed observations from yesterday's lab along with any questions about the lab, graph, or post-lab questions.
Tomorrow we'll hopefully have a couple of new demonstrations (I haven't done them before) and I will try to address some of the questions on the lab that you were asked to make educated guesses about. We'll also have some notes on phase changes and try to use data from your lab to support the ideas discussed. Homework will be review problems; they will be posted online tomorrow.
I have been asked by several folks to put up a new optional assignment, and the one I was hoping to use for meteorology isn't going to work. Here's an alternate - there are two different pages you'll need.
worksheet
scoring guide
I'll try to give you some good ideas for this in class early next week, and put a list up online of some good ideas to help you out. Due date for this is Friday, April 13th.
Tuesday, March 27, 2012
Water's Specific heat... and Sublimation of CO2
Today we reviewed the concept of specific heat and modeled objects with different specific heats - soil vs. water. Depending on the class, we either heated these objects or allowed them to cool. We found that the soil changed its temperature more rapidly than the water - signifying that its specific heat (resistance to temperature change) is less.
This relates to maritime/continental climates - your book explained that maritime climates are more moderate/stable than continental due to water's presence, and that matched the data we saw in class today - temperature of dry land soars in the daytime, then drops sharply at night, while water temperatures are slightly warmer in day and cooler at night, with a much smaller range.
Second, we got to work with dry ice... Carbon Dioxide that's been cooled until it is frozen solid. At its surface, it sublimes (turns directly to gas) at a temperature of around -80C or -110F. COLD! Your body temperature is 37C, room temp is about 20C, and you know 0/100C as water's freeze/boil points. Sublimation does happen with regular ice, but carbon dioxide completely skips the liquid stage, with absolutely no liquid being produced at all - pretty cool!
We looked at the clouds forming around dry ice for a bit (just water vapor turning to clouds/fog in nearby air as it cools and gives its thermal E to the ice) and then after a safety warning or two, students got to play with small pieces; making the rate increase with a conductive coin and hearing the vapors hiss away, making a dry ice air hockey puck, or just watching the ice make clouds and disappear.
Finally we had two big demonstrations; both involving adding water to the dry ice to make it sublimate faster (warm water provided more energy!) First, we made a hot water bath for the dry ice, which looked cool, then we trapped it beneath a soap bubble film... which grew until it burst and cold water vapor fell over the edge, and then we mixed dry ice, soap, and warm water to make the cleanest fun you ever had - cloud bubbles.
Tomorrow's lab will involve an official writeup in your lab journal; it will be involving safety goggles and temperature change between solid, liquid, and gas of water. We will also do some fun informal lab activities on the sidelines during tomorrow's lab, both involving states of matter and energy with ice/water.
This relates to maritime/continental climates - your book explained that maritime climates are more moderate/stable than continental due to water's presence, and that matched the data we saw in class today - temperature of dry land soars in the daytime, then drops sharply at night, while water temperatures are slightly warmer in day and cooler at night, with a much smaller range.
Second, we got to work with dry ice... Carbon Dioxide that's been cooled until it is frozen solid. At its surface, it sublimes (turns directly to gas) at a temperature of around -80C or -110F. COLD! Your body temperature is 37C, room temp is about 20C, and you know 0/100C as water's freeze/boil points. Sublimation does happen with regular ice, but carbon dioxide completely skips the liquid stage, with absolutely no liquid being produced at all - pretty cool!
We looked at the clouds forming around dry ice for a bit (just water vapor turning to clouds/fog in nearby air as it cools and gives its thermal E to the ice) and then after a safety warning or two, students got to play with small pieces; making the rate increase with a conductive coin and hearing the vapors hiss away, making a dry ice air hockey puck, or just watching the ice make clouds and disappear.
Finally we had two big demonstrations; both involving adding water to the dry ice to make it sublimate faster (warm water provided more energy!) First, we made a hot water bath for the dry ice, which looked cool, then we trapped it beneath a soap bubble film... which grew until it burst and cold water vapor fell over the edge, and then we mixed dry ice, soap, and warm water to make the cleanest fun you ever had - cloud bubbles.
Tomorrow's lab will involve an official writeup in your lab journal; it will be involving safety goggles and temperature change between solid, liquid, and gas of water. We will also do some fun informal lab activities on the sidelines during tomorrow's lab, both involving states of matter and energy with ice/water.
Monday, March 26, 2012
Phase Changes & Energy.. Water
Today in class: Notes: Phase Changes - below.
Questions from Lab - turn in if complete
Review compressibility of liquid/gas AND try again to make clouds.
Discuss briefly lab tomorrow - safety glasses, etc.
Videos - some classes saw video demonstrations on energy and phase change, some classes saw video on storm chasers
Phase Change Notes:
Common phases:
Solid, Liquid, Gas (also Plasma - excited gas)
Low E--> more E
Energy expended or absorbed between phases: Melting/freezing (fusion)
vaporization / condensation
Water requires huge amounts of E to change Temp or Phase
Resistance to temp change: Specific Heat ("thermal inertia")
Water = very high specific heat
Lab tomorrow!
Questions from Lab - turn in if complete
Review compressibility of liquid/gas AND try again to make clouds.
Discuss briefly lab tomorrow - safety glasses, etc.
Videos - some classes saw video demonstrations on energy and phase change, some classes saw video on storm chasers
Phase Change Notes:
Common phases:
Solid, Liquid, Gas (also Plasma - excited gas)
Low E--> more E
Energy expended or absorbed between phases: Melting/freezing (fusion)
vaporization / condensation
Water requires huge amounts of E to change Temp or Phase
Resistance to temp change: Specific Heat ("thermal inertia")
Water = very high specific heat
Lab tomorrow!
Thursday, March 22, 2012
Coriolis & Prevailing Winds, E in atmosphere Labs - HMWK
Today we had a lab involving solar energy reaching the Earth (and other planets) and hopefully in your post-lab work (homework - not much class time will be available to complete them tomorrow) you will get an appreciation of how light intensity relates to distance from a light source, and how the angle of that light relates to intensity as it is spread over a greater or smaller area.
We will spend a brief bit in class tomorrow relating lines of latitude to the angles you measured and worked with during today's lab.
Labs tomorrow and Monday: Phase changes and energy - Latent heat, manipulations of pressure,state
Tuesday and Wednesday we practiced using the Coriolis effect to predict winds on pressure maps, finished a video outlining general principles of Meteorology, and discussed how fronts cause rain, how convection at the Earth's equator sets up global convection currents and the Coriolis effect acting on these works to produce prevailing winds - trade winds, westerlies, and polar easterlies.
Some recommended images:
We will spend a brief bit in class tomorrow relating lines of latitude to the angles you measured and worked with during today's lab.
Labs tomorrow and Monday: Phase changes and energy - Latent heat, manipulations of pressure,state
Tuesday and Wednesday we practiced using the Coriolis effect to predict winds on pressure maps, finished a video outlining general principles of Meteorology, and discussed how fronts cause rain, how convection at the Earth's equator sets up global convection currents and the Coriolis effect acting on these works to produce prevailing winds - trade winds, westerlies, and polar easterlies.
Some recommended images:
Monday, March 19, 2012
Why and where does the WIND blow? & Thurs HMWK
Advance notice of homework for Thursday: Read p. 524-533 (ignore the stuff on p. 525 about Coriolis) and work p. 528, #1-4,7 and p.534#1,2,5,6.
Today in class: notes/discussion on Wind - how, why, and where it blows
We made predictions about wind based on H and L pressure on maps, learned how the Coriolis effect makes it appear like winds curve to the R in the northern hemisphere and L in the southern, and how this looks on a weather map.
Be sure to pay attention to forecasts at home this week if you get the chance to watch the news - see how what you know from class plays into understanding how things are predicted to move on the weather maps and what is predicted to happen!
Today in class: notes/discussion on Wind - how, why, and where it blows
We made predictions about wind based on H and L pressure on maps, learned how the Coriolis effect makes it appear like winds curve to the R in the northern hemisphere and L in the southern, and how this looks on a weather map.
Be sure to pay attention to forecasts at home this week if you get the chance to watch the news - see how what you know from class plays into understanding how things are predicted to move on the weather maps and what is predicted to happen!
Tuesday, March 13, 2012
E in the Atmosphere, Wed HMWK
Due Wednesday: Read p. 518-522, p. 522#1-7
Today in class: notes/discussion: Energy in the Atmosphere: Meteorology
Discussed high-altitude low-budget photo - upon further research after someone asked - apparently it's not illegal maybe? If someone wants to look into this and try it, I'm game.
Discussed/cartooned the rain shadow effect and how energy/work relates to it.
Tomorrow we'll discuss answers on the homework and do some scientific method / graphing discussion, and maybe work a lab /demonstration involving phase changes if I can get it worked out.
Today in class: notes/discussion: Energy in the Atmosphere: Meteorology
Discussed high-altitude low-budget photo - upon further research after someone asked - apparently it's not illegal maybe? If someone wants to look into this and try it, I'm game.
Discussed/cartooned the rain shadow effect and how energy/work relates to it.
Tomorrow we'll discuss answers on the homework and do some scientific method / graphing discussion, and maybe work a lab /demonstration involving phase changes if I can get it worked out.
Monday, March 12, 2012
Magnetism review/quiz, HMWK- next unit: E in atmosphere
New optional assignment. Due 3-23: Faraday&Magnetism
Another optional assignment. Due 3-23: Greenhouse Effect
Due Wednesday: Read 518-522; p. 522#1-7
Today classes turned in weekend homework, we discussed answers, and had a quiz on Magnetism - much of the content came from in-class experiences and lab activities, but could be understood from notes and reading the book as well for background as to why things acted as they did.
We also had time in some classes to discuss graph types (still a problem for ~50% of my students in labs) and the rules I proposed follow below.
Our next unit is Meteorology: a study of Energy in the Atmosphere - we'll use many of our understandings of energy in other aspects to analyze and hopefully understand processes that control the fluid we live in.
Graphing reminder:
Bar graphs: used for comparison between non-numerical groups. There are no numbers on the x-axis for this type of graph.
Line graphs / Scatter plots: Used for showing a relationship between different variables. Quantities, time, temperatures, etc. may be among the things that arrive on the X- axis, but these have one thing in common: There are numbers on the X-axis, and these numbers mean something - the data can potentially be turned into a line of best fit and a slope. Someone told many of you to use line graphs when time was used on the x-axis. This is usually true but it obviously isn't the only case!
We'll work through examples Wednesday and Thursday this week.
Another optional assignment. Due 3-23: Greenhouse Effect
Due Wednesday: Read 518-522; p. 522#1-7
Today classes turned in weekend homework, we discussed answers, and had a quiz on Magnetism - much of the content came from in-class experiences and lab activities, but could be understood from notes and reading the book as well for background as to why things acted as they did.
We also had time in some classes to discuss graph types (still a problem for ~50% of my students in labs) and the rules I proposed follow below.
Our next unit is Meteorology: a study of Energy in the Atmosphere - we'll use many of our understandings of energy in other aspects to analyze and hopefully understand processes that control the fluid we live in.
Graphing reminder:
Bar graphs: used for comparison between non-numerical groups. There are no numbers on the x-axis for this type of graph.
Line graphs / Scatter plots: Used for showing a relationship between different variables. Quantities, time, temperatures, etc. may be among the things that arrive on the X- axis, but these have one thing in common: There are numbers on the X-axis, and these numbers mean something - the data can potentially be turned into a line of best fit and a slope. Someone told many of you to use line graphs when time was used on the x-axis. This is usually true but it obviously isn't the only case!
We'll work through examples Wednesday and Thursday this week.
Friday, March 9, 2012
Magnetic Phenomena, Weekend HMWK
(2nd hour does not have homework)
Homework for Monday: p. 450, #1-15, 23, 24, 26, 27
Freshmen Women interested in Engineering: Washington University's Catalysts For Change workshop is March 24 & 31; see the flyer in my classroom for more info or email them here to reserve a spot.
We will have a small quiz Monday on Magnetism and then we'll start our next unit (Energy in the atmosphere - Meteorology) I have decided to limit our studies in the remainder of the year to two other units after Meteorology - Astronomy and Waves. We'll also have some unofficial units that are smaller covering topics involved with geology, theoretical physics, fluid physics, and pre-Chemistry. These will not be tested in official units; material from these will appear only on quizzes, homework and your Cumulative exam which will be held right before the last days of school when "finals" are held.
Today in class: Magnetic Phenomena - is Copper magnetic / can it be made to be magnetic?
The main theme was answering this question, and "yes, kind of...." was the answer - Moving charges create magnetic fields, and moving charges within a magnetic field experience a magnetic force. Between these two ideas, we connected our knowledge and experience with electromagnets, magnetic fields, and motors to new phenomena: copper and zinc (pennies) being affected by magnets (only while in motion!) and copper pipes acting to slow the descent of magnets when dropped through them.
After that, we played Magnetism Jeopardy! A fun way to end a fun week with magnetism.
Homework for Monday: p. 450, #1-15, 23, 24, 26, 27
Freshmen Women interested in Engineering: Washington University's Catalysts For Change workshop is March 24 & 31; see the flyer in my classroom for more info or email them here to reserve a spot.
We will have a small quiz Monday on Magnetism and then we'll start our next unit (Energy in the atmosphere - Meteorology) I have decided to limit our studies in the remainder of the year to two other units after Meteorology - Astronomy and Waves. We'll also have some unofficial units that are smaller covering topics involved with geology, theoretical physics, fluid physics, and pre-Chemistry. These will not be tested in official units; material from these will appear only on quizzes, homework and your Cumulative exam which will be held right before the last days of school when "finals" are held.
Today in class: Magnetic Phenomena - is Copper magnetic / can it be made to be magnetic?
The main theme was answering this question, and "yes, kind of...." was the answer - Moving charges create magnetic fields, and moving charges within a magnetic field experience a magnetic force. Between these two ideas, we connected our knowledge and experience with electromagnets, magnetic fields, and motors to new phenomena: copper and zinc (pennies) being affected by magnets (only while in motion!) and copper pipes acting to slow the descent of magnets when dropped through them.
After that, we played Magnetism Jeopardy! A fun way to end a fun week with magnetism.
Thursday, March 8, 2012
Tues-Thurs: Magnetic Fields and Motors
Tuesday Mr. F. was absent; classes watched a video on magnetism and worked on a scientific method review worksheet (in addition to Monday's posted homework assignment).
Wednesday labs and homework were turned in, and we experimented with magnetic fields - showing where they are on a magnet, how they're shaped, and how they react to being in the presence of multiple magnets with iron filings inside glass jars and with some magnetic fluid - a knockoff of FerroFluid. We also tried to verify where the N and S poles of a magnet are using a compass, and figured out how a compass reacts when placed in various locations around a magnet (it lines up with the magnetic field lines we drew in our notes!)
Today we went over answers to the homework turned in on Wed. and answers to the scientific method review WS. If you had a disc magnet, you also got some fun toys to work with - the makings of a homopolar motor - another cool version here.
Tomorrow in class we'll share findings from the electromagnet lab, discuss graph types and lab grades (some of you aren't looking at past labs) and have a fun assessment of magnetism studies - a Jeopardy game. Classes who are uncooperative will earn a traditional quiz.
Wednesday labs and homework were turned in, and we experimented with magnetic fields - showing where they are on a magnet, how they're shaped, and how they react to being in the presence of multiple magnets with iron filings inside glass jars and with some magnetic fluid - a knockoff of FerroFluid. We also tried to verify where the N and S poles of a magnet are using a compass, and figured out how a compass reacts when placed in various locations around a magnet (it lines up with the magnetic field lines we drew in our notes!)
Today we went over answers to the homework turned in on Wed. and answers to the scientific method review WS. If you had a disc magnet, you also got some fun toys to work with - the makings of a homopolar motor - another cool version here.
Tomorrow in class we'll share findings from the electromagnet lab, discuss graph types and lab grades (some of you aren't looking at past labs) and have a fun assessment of magnetism studies - a Jeopardy game. Classes who are uncooperative will earn a traditional quiz.
Monday, March 5, 2012
More Magnetism, Wed HMWK, bring 50 cents Wed.
Wed HMWK: Read p. 431-433; p. 437#1-3 AND read p. 442-444; p. 444#1-2,4-6.
Today's exam went well with the high score being 46/50 (in 5th hour) and a few folks hitting 43/50, so the curve was set to 43 points possible. Grades should be updated on Edline now; I can't export them manually so hopefully the principals have done so as they are sending 3rd quarter grades out now.
Tomorrow all classes will watch a video on Magnetism and then will have time to work on their lab or work on Wednesday's homework.
on Wednesday labs are due; we will also start a new lab involving magnetic fields. Be sure to bring 50 cents on Wednesday so you can get some disc magnets; these will be nice to use in the lab and I will send you home with something else that's pretty cool to use with them.
Thursday we'll wrap up the magnetic field lab and maybe play some Jeopardy if time permits.
Friday's class will be busy talking about energy usage and conservation, etc. and will have a related optional assignment. Next week we'll make a rather harsh jump into Energy in the Atmosphere: Weather.
Today's exam went well with the high score being 46/50 (in 5th hour) and a few folks hitting 43/50, so the curve was set to 43 points possible. Grades should be updated on Edline now; I can't export them manually so hopefully the principals have done so as they are sending 3rd quarter grades out now.
Tomorrow all classes will watch a video on Magnetism and then will have time to work on their lab or work on Wednesday's homework.
on Wednesday labs are due; we will also start a new lab involving magnetic fields. Be sure to bring 50 cents on Wednesday so you can get some disc magnets; these will be nice to use in the lab and I will send you home with something else that's pretty cool to use with them.
Thursday we'll wrap up the magnetic field lab and maybe play some Jeopardy if time permits.
Friday's class will be busy talking about energy usage and conservation, etc. and will have a related optional assignment. Next week we'll make a rather harsh jump into Energy in the Atmosphere: Weather.
Friday, March 2, 2012
end of 3rd Quarter
Well, grades won't be updated online until Monday - I got kicked out of school today earlier than I was expecting as the custodians worked the day shift since we had no students today. For those of you who were hoping to have some final touches made to your grade, you won't see them until Monday. My apologies.
Although I left in a hurry as Dr. Rossiter set the school alarm and left my grading work there, I did take time tonight to illustrate the value in doing non-required work (besides the obvious extra review/extension/application that helps on the tests):
A Case Study: Optional Assignments
Joe All Optional and Jane No Optional are two students in my class. Both students do all their homework and generally do well on tests. Both Joe and Jane have 100% in the class, but Joe has done every optional assignment and also his labs have been done well; all getting 100%. Jane has earned 100% on every required assignment but no extra/optional work. On Monday's test, both Joe and Jane have a bad day and score a 25/45. Joe's grade drops to a 93%, but Jane's grade has less buffering from all the optional points and drops to an 88%. The effect will be similar no matter where your grade is; doing work (well) and getting high marks on optional assignments is like inertia for your grade. Not keeping it down inertia, keeping it up.
Although I left in a hurry as Dr. Rossiter set the school alarm and left my grading work there, I did take time tonight to illustrate the value in doing non-required work (besides the obvious extra review/extension/application that helps on the tests):
A Case Study: Optional Assignments
Thursday, March 1, 2012
Study...Exam Monday! Review Materials here!
Study: magnetism TGT game Electricity TGT game Review your notes, the textbook, your homework problems and answers, this blog, and have your equation card with the equations for Power and Ohm's law handy.
Tuesday we worked with the right hand rule and got compasses to match our predictions (hopefully), as well as finished notes on magnetism.
Wednesday and Thursday classes had time to make and play with electromagnets, and then manipulate them in an investigation: Electromagnet Experimentation Lab (due Wed.)
Monday we will have our exam; it will probably be all multiple choice as I will be taking many of the free-response questions and adding them to a small magnetism quiz for a week later. Tuesday and Wednesday we will be using magnets more, so be sure to bring them to class!!!! Tuesday we'll start a magnetic field lab (you will enjoy - it's fun!) and Wednesday be sure to bring a quarter to class if you haven't purchased a disc magnet from me - we'll be making your magnet into a motor with just a couple more parts, all of which you can take home and show your folks/friends with a spare battery lying around the house. Very fun stuff.
Tuesday we worked with the right hand rule and got compasses to match our predictions (hopefully), as well as finished notes on magnetism.
Wednesday and Thursday classes had time to make and play with electromagnets, and then manipulate them in an investigation: Electromagnet Experimentation Lab (due Wed.)
Monday we will have our exam; it will probably be all multiple choice as I will be taking many of the free-response questions and adding them to a small magnetism quiz for a week later. Tuesday and Wednesday we will be using magnets more, so be sure to bring them to class!!!! Tuesday we'll start a magnetic field lab (you will enjoy - it's fun!) and Wednesday be sure to bring a quarter to class if you haven't purchased a disc magnet from me - we'll be making your magnet into a motor with just a couple more parts, all of which you can take home and show your folks/friends with a spare battery lying around the house. Very fun stuff.
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