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Secular Science Resources for Homeschoolers

Honors Chemisty 02 – Recrystalization

Todays lab, Recrystalization, is from the CK01A Instruction manual that goes along with the Honors Chemistry kit.   You can download the manual for free from the Home Scientist website by clicking on the link above.  In this lab the students mix some sodium bicarbonate (baking soda)  and sodium chloride (salt), then slowly add it to cold water until the solution is saturated. They then heat the water until it boils and add more mixture until its saturated again. IMG_4062 We then let the solution cool and watch crystals form on the surface and sides of the beaker.  IMG_4067Once the beaker has cooled we placed it in the freezer to further cool the supersaturated solution and let even more crystals form.  Some of the liquid  is then poured off into a test tube, while the crystals are rinsed with cold water and then laid out to dry on paper towels.  IMG_4068The students then put a few drops of HCl into the test tube to test for the presence of baking soda,  the HCl reacts with sodium bicarbonate and forms salt, water and carbon dioxide, the last of which is a gas and forms bubbles.  Everybody got lots of bubbles because even though some of the sodium bicarbonate crystallized out of solution, the solution still contains a lot of it.

The students measured the mass of the salt and baking soda mixture before they started adding it to the water, and measured it again each time the solution was saturated so they could calculate the mass of material dissolved in their solution.   We have two hours for class and ran out of time, it would have been nice to leave the solutions in the freezer longer but class was over so we had to rush a bit at the end.

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I recommended the students watch Crash Course Chemistry #21 lab techniques

and a video by Tyler DeWitt on scientific notation.

Intro Chem 02 – Temperature

For the second class I used a lab, Molecules in Motion,  from the American Chemical Society’s Middle School Chemistry curriculum, which is free on their website.  The purpose of todays class was to get across that temperature is related to the kinetic energy (energy of motion) of the molecules and learn how to read a thermometer in Celsius and Fahrenheit.  I had a plastic cup of marbles that I jiggled gently and explained that molecules are always in motion and if I heated them up they would move even faster (shake cup vigorously).  I then asked the students what they observed about the marbles at ‘higher temperature’ and they quickly answered that they were moving faster and that they were moving higher up in the cup… taking up more space!  At which point I explained that’s exactly how a thermometer works.  The molecules in the red liquid get hotter, their motion increases and they need more room so it moves up the tube in the thermometer.  The Molecules in Motion lab has the students drop 2 drops of food coloring, one yellow and one blue,  in both a cup of hot water and a cup of cold water.  The students correctly predicted that the colors would mix faster in the hot water.IMG_4033

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The food coloring just sank to the bottom of the cold water while the colors mixed fairly quickly in the hot water.  Even after a few minutes when the hot water had turned completely green from the  mixing colors, the cold water was divided, with blue in one half and yellow in the other half.  This was a really nice experiment.  We had dropped food coloring in water before but never the two different colors, it really gets the point across.IMG_4045.jpg

The second activity  was based on a lab we did a few years ago using Science Fusion Module H, Understanding Temperature Scales.  The labs for Science Fusion are only available if you have online access. They are not in the books.  Anyway its bascially learning how to read a thermometer.  The students used thermometers to measure the temperature in Celsius and Fahrenheit of boiling water, warm tap water, room temperature, cold tap water, and ice water.   Then they had to graph the temperature in Fahrenheit as a function of the Celsius temperature.   This proved a challenge since most of them had not made graphs before – hence the activity.  Kids always have a hard time using graph paper and just want to randomly put tick marks on the paper, not realizing they need to make the distance between the tick marks the same or the graph won’t work.   Once they had their data plotted I showed them how to draw the best line and they used their graphs to convert from one temperature scale to the next.

So three main ideas today: 1) temperature is related to the motion of the molecules, 2) learned how to read a thermometer and got a feel for Celsius scale, and 3) learned how to make a graph.

For those looking for a fun science textbook for your middleschooler, Ian Guch has started putting chapters of his text, Physical Science: A Smorgasbord of Knowledge, up on his website for FREE.  We started reading Ian Guch’s high school chemistry book, Chemistry, the Awesomest Science, last week and my son compared it to Mark Watney from The Martian, but instead of a botanist, he’s a chemist.  If you haven’t read The Martian, then shame on you.

Honors Chemistry 01 -Separating Mixtures

lab notebookThe high school honors chemistry class for homeschoolers started today.  First we went over what goes in the lab notebook.  I had already asked the students to read the section on lab notebooks in the Standard/Honors Home School Chemistry Laboratory Kit CK01A Instruction Manual, by the Home Scientist so I just quickly went over the highlights.  These lab books will be the proof that the student completed a LAB course and can be brought to college interviews to show that they did REAL labs, so its important they write down everything they do (procedure) and of course their data and results (good and bad).  We also went over a bit of safety, I showed them where the fire extinguisher is kept and explained how to use it.  Showed them the vinyl aprons we have to protect our clothes and asked the kids with long hair to pull it back to keep it out of chemicals and flames.   I also plan on emailing them a MSDS, Material Safety Data Sheet, before class for each of the chemicals we will use that week and told them to note in their lab books any hazards they need to be aware of for that class.

IMG_3969The lab today was Separation of a Mixture found in Chapter 2 of Ian Guch’s 24 Lessons That Rocked the World.  The students were each given a large spoonful of a mixture (photo on left) containing sand, salt and pepper and that they had to separate into its separate components.  I had a variety of equipment out on the counter and told them to ask if there was something else they wanted to use.  Many of the kids knew right off the bat that pepper would float, so they poured distilled water into their beaker containing the mixture.  The pepper floated, the salt dissolved and the sand sunk to the bottom….for the most part. We didn’t use pure sand so we ended up with a few floaters from the sand as well, but for the most part it worked.  The students skimmed off the pepper by pouring it carefully into a coffee filter in a funnel.  IMG_3937Now they had to get the salt out of the water, so they poured some of the salt water into an evaporating dish or crucible and put it over a heat source.  I have 3 heat sources, a hot plate, a wickless alcohol burner and a microburner (butane).  Each one worked fine, though the microburner, in the photo below, was the most impressive and it was really nice being able to control the size of the flame, which you can’t do with the alcohol burner. The microburner was also very easy to fill. I may have to buy another one of those. IMG_3944 One thing to watch out for is that when the water is almost gone the salt started splattering out of the cruicible and made a mess, so you may want to stop before it gets to that point.

Students put the filter papers with sand and pepper outside in the hot sun to evaporate the last of the water and the salt was left in the cruicibles.  We ended up with brown salt and I challenged the students to figure out what was causing the color.  IMG_3954When we poured water over the mixture the water turned brown, so it could have been the pepper or the sand tainting the water.  Students took small samples of just sand and just pepper and put them in  beakers with water.  They found the pepper turned the water brown and the sand turned the water gray!  This was when I remembered I had used the tray of sand for a different chemistry experiment a few years ago and that there was ash mixed in with the sand, hence the gray water and floaters from the sand.

If they finished the pepper mixture, they were challenged to try to separate a mixture of salt and sugar.  One group used isopropyl alcohol and found that sugar dissolves in alcohol, but not salt!  We all got a lesson in safety when they decided to get the sugar back by heating the alcohol over a burner.  The resulting alcohol lamp they created when the liquid in the evaporating dish burst into flames was quite impressive and made one student exclaim, “This class is going to be so awesome!” Luckily there was only a little bit of isopropyl alcohol in the evaporating dish so the flame went out pretty quick, but I’m fairly certain all the students now know to keep alcohol away from the burners and they’ve all concluded this is going to be an exciting class.  I was impressed that the kids all kept their cool and just stepped back, after turning off the microburner, to wait for the alcohol to burn up.

519VDAS2RZL._SX317_BO1,204,203,200_For homework this week I gave the kids some problems from Caveman Chemistry by Kevin M. Dunn.  I had just enough time to go through the first problem before class ended, and asked the students to do some more of the problems at home to give them practice converting units.  I haven’t read all of Caveman Chemistry yet, but its a unique approach in teaching chemistry along with some basic skills, like making fire with a bow drill, flint knapping and making mead. The author also  has a good sense of humor so its an entertaining read so far.

Before class I had asked kids to read Chapter 1 in Modern Chemistry textbook and/or watch Crash Course Chemistry 1 and 2.

Or if they prefer Tyler Dewit, he has some videos on unit analysis.

Intro Chem 01 – Mass & Density

Today was the first day of my chemistry class for younger homeschoolers.  The kids range in age from 10-13.  I plan on using the American Chemical Society’s free Middle School Chemistry curriculum and supplement with Ian Guch’s chemistry lessons and some labs/lessons from Middleschoolscience.com.  The ACS’s curriculum is mostly labs but it does have some sections at the end of each chapter that the kids can read if so inclined.

Last year I had the middleschool kids do an interactive notebook in the Big History class and it went so well I decided to do one for the chemistry class this year. The big history kids seemed proud of their ‘fat’ books at the end of the year and it certainly gives the homeschool parent an easy way to show off the school work.  We also don’t have a real textbook again so this way the kids can make their own.  So for the interactive notebook part, I bought the $40 Highschool Bundle for chemistry from Bond with James on TeacherspayTeachers  – its currently on sale for $34.  I bought the high school bundle because I’m also teaching a high school honors chemistry class and its the same as the middle school bundle but with a few extras.  I haven’t looked at it all, but so far I’m pretty happy with my purchase and have found stuff I want to use for both classes.

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After having the kids decorate their composition notebooks with scrapbooking paper, duct tape and caution washi tape, I repeated the bottles of stuff lab I did earlier this summer with the young physics class.  I prepared some empty plastic bottles before class – filIed them with yarn, cotton balls, water, rocks, etc., and the students brought bottles filled with rice, beans, kitty litter and beads.   I changed up the data sheets a bit from middleschoolscience.com because I knew we’d only have 5 or 6 bottles for group and made one data table for the whole lab, including volume and density.  The main point of this activity was to get the kids used to working with grams  and to get an idea for what 50 g or 500 g feels like.

They also learned how to use the triple beam balance and a digital scale.  Some of the bottles were filled with rocks and were too heavy for the triple beam balance.

IMG_3918We talked about density a bit and I made a 6 layer density column in a graduated cylinder.  The instructions for this can be found on Steve Spangler’s site (among others).  I mainly did this because the Bond with James interactive notebook stuff had a great little cut and paste activity for just this activity.  The kids cut out a blank cylinder and then cut and pasted different rectangles labeled with different densities in the correct order on the cylinder.  The students  had to think about whether the highest densities would go on the bottom or the top of the cylinder. It helped that the lowest density was wood so when they asked for help, I just asked them if wood would float or sink and they all knew it would float and it had the lowest density, so it went on top.

Before class I recommended families watch the following video, Chemical Curiosities,  from the Royal Institute in England. Its a great lecture filled with some amazing chemistry demonstrations.

 

RSO Physics 08 – Light

The title is a little misleading because today’s class had nothing to do with the Real Science Odyssey Physics curriculum.  This was the last class of the summer and since most of the kids in the class already seemed to know a lot of the science we had been discussing I decided to do my light lecture for older kids.   We discussed how light is a wave and why objects appear to be a certain color. For example, a blue ball looks blue because it reflects blue light and absorbs the other colors.  I then asked why is the sky blue?  Quite a few of them knew it had something to do with the atmosphere, but couldn’t really explain it, so I showed them my big tank of science… an aquarium filled half way with water and a bit of powdered milk mixed in.  The powdered milk helps scatter the light.  You can see in the first photo the milky water looks very blue near the flash light because the particles floating in the water are predominately scattering blue light.  But if you look at the flashlight from the far end of the tank it looks orange/yellow… kind of like a sunset.  When the sun sets the light reaching our eyes has gone through a lot of atmosphere (or a lot of milky water) before we see it and all the blue light has been scattered away, leaving behind the yellow/red colors.  This is also why sunsets are more spectacular when there is a wildfire or volcano because there are more particles in the air scattering light.

After explaining polarized light with the help of some pvc (check out this link  and photo below from Scientific Exploration with Paul Doherty)  I  polarizerparllori300gave each student a set of polarizers and showed them how when they are crossed they can block out all the sunlight.  Then we put plastic forks between the crossed polarizers and you could see ‘rainbows’ of a sort in the plastic where it was stressed.  This happens because the plastic is optically active, the light is actually rotated a bit as it passes through the plastic so it can now pass through the second polarizer.

We also talked about how rainbows are formed, how our eyes work and what it means to be color blind.  There’s a great app on the iPad, ColorDeBlind,  that lets you see how the world would look if you were colorblind.  It doesn’t mean you just see black and white, it means that one set of color sensing cones isn’t as sensitive as its supposed to be.  For some that means they have trouble seeing red, so a light pink shirt may look the same as  a white shirt to them.  Below is a picture I took with the app.  The image on the left is what people with ‘normal’ vision see, and the image on the right is what a red-green color blind person might see.  Notice all the reds and greens are gone but the blue stickers on the fruit still appear very blue. This really blew the kids away.  colorblind

Physics Girl has a nice video explaining the physics of rainbows.

And the Royal Institute has a video called Light Fantastic: The Science of Color that covers a lot of these same topics.

This concludes this set of physics posts.  I did not use the whole Real Science Odyssesy Physics curriculum since I was just teaching a short summer class.   The kids I had in this class were already pretty versed in science, especially for only being 8 or 9 years old and they probably could have done with a little more meat in the curriculum.  But if your kid has never done a science class  this  curriculum would be pretty easy to implement at home.

 

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