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Solar Eclipse Class

With the upcoming solar eclipse I decided to teach a class for local homeschoolers and it filled so fast I ended up teaching three classes!  I started out by talking about the scale of our solar system and showed them this picture of the planets and asked them what was a57f24789eed987c20c6bce24542783dwrong with it.  Many realized the size of the planets was all wrong compared to each other and the sun.  The distances are obviously wrong as well since the planets are very far the sun and they are not equally spaced.  To make a model of the solar system to scale, I have a large exercise ball which is half a meter across and we used that as the sun. I then asked the students what size they thought the Earth would have to be for our model.  A few kids thought baseball size, a few thought it should be the size of a quarter, but its actually only 0.46 cm across!  I then asked the students where should we put the earth if we want our model to be accurate?  Should it be right next to the sun (green ball)?  A few feet away?  In the kitchen?  It needs to be  at the end of the culde sac across the street!  IMG_0757This kind of blows their minds because its sooo small (the tiny blue ball in the photo to the right) and needs to be so far away to be to scale.  The other planets are shown to scale with the sun in the photo – but not the right distances.  I showed the kids images of my house on google earth with the orbits of the planets drawn on it to scale and for the furthest planets we needed to be looking at a map of the city.

The photo below from wikipedia shows the planets to scale in size but the distances are not correct.  Its pretty much impossible to show both the size of the planets and distances in a meaning image that will fit on a piece of paper.Planets2013.svg

The first activity we did was to make a model of the Earth and moon to scale.  We used 1inch foam balls (painted blue and green) for the Earth and 1/4 inch pony beads for the moon.  The ball and bead were put on toothpicks and then clamped with bulldog clips to a square dowel (36 inches long, 1/4 inch wide) 30 inches apart.  This is roughly to scale.  We then went

outside and used the real sun (if it wasn’t cloudy) as our light source.  Students were able to make lunar eclipses (photo on right), where the shadow of the earth covers the moon and solar eclipses (photo on left), where the small shadow from the moon makes a small dot on the Earth.  We talked about how to see the solar eclipse you have to be standing in the shadow (the black dot on the earth ball, but to see a lunar eclipse you just have to be on the night time side of the earth.  This activity can be found in the Solar Eclipse Activity Guide put out by NASA.

IMG_1483Students also made pinhole viewers (directions can again be found in the NASA guide above). Basically you put two hole in one end of the box and tape white paper inside the other end to be your projection screen.  Then you cover one of the holes you made with foil and using a tack make a very small round hole in the foil.    To use the pinhole viewer you stand with your back to the sun, let sunlight enter the pinhole and fall on the projection screen while looking through the other hole that you made.

Students also made eclipse art, yet another activity from the NASA guide.   For this you hold down a circle of cardstock on top of dark paper and then draw around the circle with oil pastel (or chalk) and then using your fingers, smear the pastel outwards to make a corona.  The kids made some great eclipse drawings with this method.

Each student was also given a pair of solar eclipse glasses to take home so they can use them to watch the eclipse.  I actually bought some plastic onesfor my family so they fit over regular glasses and stay on better (update: just got notified that these might not be safe so Amazon refunded my money). The cardboard ones tend to fall off so you have to hold them on.   IMG_1485

Here’s some great videos on solar eclipses.

 

 

 

Physics 2017-2018

I’ve decided to teach physics again this fall.  For high school physics I’m going to use UnknownLouis Bloomfield’s How Thing Work: The Physics of Everyday Life, the 5th edition.   This book is algebra based, no calculus.  I used an earlier version of this book many years ago for a college course for non-science majors and I thought it was a nice change from the usual textbook.  Its been updated with more pictures and color.  The labs we’l do in class will be very similar, if not the same, as the last time I taught highschool physics.    I am looking to buy a few sensors from Vernier that work directly with iPads.  They have a thermometer that will send data directly to their app on your iPad which would have been nice to have last year for chemistry.  They also have a force & acceleration sensor which we could make good use of in physics class.  They’re supposed to be out in a few weeks and the prices look reasonable, with some as low as $50.

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The last time I taught physics (two years ago) we used Light and Matter by Benjamin Crowell and I just saw he has a Conceptual Physics textbook on his website so will recommend that to my students as another text to look at.  Crowell has both of these available on his website as pdfs that you can download for free.

lab notebook

I also recommend the students get the Cartoon Guide to Physics by Larry Gonick and a nice lab notebook.

I’l also be teaching a physics class for younger kids (11-13 years old) using Science Fusion Module I (Motion, Forces & Energy) and Module J (Sound & Light).  You can buy these books from Amazon for $15 or less or buy them as part of a homeschool package on the Homeschool Buyers’ Co-op for roughly $37 each and you’l get the book and online access to digital resources, including an inactive book, labs, etc.  I used these books back in 2013 so I already have all the materials downloaded which will make my life easier.  These books are soft covered books and the students are meant to write in them as they go through them.  Not quite a workbook, but enough to hopefully keep kids engaged and the online access is worth it if you’re kid prefers learning on a computer or might have trouble reading it themselves.

 

These classes will start near the end of August and I will post about the labs and activities we do after each class.

Honors Chemistry 31 – Nuclear Chemistry

This is one of my favorite chemistry topics since its also a topic in physics.  I pulled out an old slide show on nuclear physics, different types of nuclear reactions, fission, fusion, atomic bombs, power plants, all the good stuff.  We did the activities ‘Simulation of Nuclear Decay Using Pennies and Paper’, from the Modern Chemistry curriculum and built cloud chambers.

For the paper activity,  I precut a bunch of paper strips from colored card stock and gave each IMG_9880student two strips.  They placed the first strip on a graph to represent 100 percent of material.  Half of that will decay in one half life so they take the second strip which is the same length as the first one and cut it in half.  Tape the half strip next to the first one.  Repeat with each remaining strip until you can no longer easily cut the strip.  For this example we made the half life 1 minute, which is about the time it took to fold and cut the piece of paper to make the next bar.

IMG_9881

The other part of this activity involved putting 100 pennies heads up in a box – this represents our ‘original’ sample of material.  Students shook the covered box 5 times and then removed all the pennies that had ‘decayed’ (turned to tails).  This should be roughly half the pennies.  They then repeated the shaking and removing of ‘decayed’ pennies til they had 1 or 0 pennies left.  Every shake was considered to be a half life of 10 minutes for the purposes of graphing their data.

IMG_9892Then we get to the fun part of class, making cloud chambers.  A cloud chamber is a closed container with an isopropyl alcohol soaked felt pad inside it (near the top or sides) and black paper on the bottom.  The alcohol forms a mist inside the container becoming super saturated near the cold bottom of the container which is sitting on dry ice.  As particles zip through the mist it produces ions and the alcohol drops condense on these ions, leaving a visible trail.  There are a lot of videos on the web explaining how to make cloud chambers.  Here are the two I like, one by Jefferson Labs uses a petri dish to make a small cloud chamber and the one on ScienceFriday has instructions for using something bigger.  The petri dish one works really well but its gets fogged up and you spend a lot of time wiping it off.  I bought the dry ice and 91% isopropyl alcohol at my local grocery store. Our best cloud chamber was built from a cheap (thin and flimsy) plastic cookie (Dunkers) container from Trader Joe’s.  IMG_9917

In the photo above you can see our radioactive rock and 4 trails from particles that were emitted from the rock. You can also see the alcohol mist/rain in the container.   You don’t need a radioactive sample to put in the container, you will see trails from muons and other particles that are zipping by us all the time.   Here’s two videos from class:

I asked students to watch these videos before class:

Physics highschool class

Light and matter coverThis honors highschool physics class was taught 2015-2016

Homeschool Physics 001

Homeschool Physics 002 – metric units and measurements

Homeschool Physics 003 – Velocity

Homeschool Physics 004 – Constant Acceleration

Homeschool Physics 005 – Newton’s 2nd Law

Homeschool Physics 006 – Friction

Homeschool Physics 007 – Projectiles

Homeschool Physics 008 – Static Equilibrium

Physics 009 – Uniform Circular Motion and Black Holes.

Physics 010 – Gravity & Kepler’s Laws of Planetary Motion

Physics 011 – Conservation of Energy

Physics 012 – Hooke’s Law

Physics 013 – Conservation of Momentum

Physics 014- Rotational Motion

Physics 015 – Ideal Gas Law

Physics 016 -Vibrations

Physics 017 – Sound Waves

Physics 018 – Waves

Physics 019- Electricity

Physics 020 -Playing with Fields

Physics 021 – Relativity

Physics 022 – Electromagnetism

Physics 023 – Atoms

Physics 024 – Nuclear Physics & Spectra

Physics 025 – General Relativity

Physics 026 – Ray Optics

Physics 027 – Lens

Physics 028 – Why the sky is blue

Physics 029 – Diffraction

Physics 030 – Polarization

Physics 031 – Probability

Physics 032 – Light is a particle?

Physics 033 -Particles are Waves?

Physics 034 – Bohr Atom

Real Science Odyssey Physics Class

Here’s a list of posts from the class I taught for young kids over the summer of 2016 using Pandia Press’s Real Science Odyssey Physics level 1.

RSO Physics 01 – measurement & mass

RSO Physics 02 – Mass & Buoyancy

RSO Physics 03 – Forces

RSO Physics 04 – Momentum

RSO Physics 05 – Newton’s 3rd Law

RSO Physics 06 – Friction

RSO Physics 07 – Air

RSO Physics 08 – Light

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George Lakoff has retired as Distinguished Professor of Cognitive Science and Linguistics at the University of California at Berkeley. He is now Director of the Center for the Neural Mind & Society (cnms.berkeley.edu).