Saturday, January 31, 2009

Science Saturday Challenge #1

Welcome to Science Saturday Challenge #1!

We'll start with something you have probably seen before: making a pH indicator.


Red cabbage (1 head)
White vinegar (1/2 cup)
Baking soda (1 tsp)
Eye dropper
Clear glass containers (at least 3)

Shred the cabbage. Put it in a medium pot and add water until the cabbage is covered. Bring to a boil and then let it cook for about 15 minutes. Really, I just watch it on the stove until the water turns a dark purple. Strain the mixture so you only have the liquid. Do whatever you'd like with the cabbage.

I got almost a quart of indicator from one small head of cabbage. That will keep in the fridge for awhile (my jar has been sitting there for several months.)

While the liquid is cooling, get out three glass containers (or more if you are testing more than baking soda and vinegar.) In each put:

1/2 c water + 1 tsp baking soda (stir to combine)
1/2 c water
1/2 c vinegar

In my pictures, I actually used a cup of water but the color will be more intense if you use less.

Once the indicator has cooled a bit, add 15 drops of it to each of the three containers.

The acid turns pink, the base turns blue, and the water will stay purple (red + blue = purple, acid + base = neutral liquid)

Why? Because cabbage and many other plants contain anthocyanins that change color depending on pH. These substances are what show through in colorful autumn leaves when the chlorophyll drains away. They are also why some plants will have different colors when planted in different soils.

Links for more information:

What are acids, basis, and pH? See if your acids and bases have these properties. Instead of vinegar, I actually added ascorbic acid to water. Ascorbic acid can be purchased through The Baker's Catalogue as a dough enhancer and to make sourdough bread more sour! What about slippery soap--any guesses as to its pH?

How Stuff Works: Where does the color come from in purple cabbage?

Acids and Bases: Frequently Asked Questions (advanced)

Water to Wine: the molecular basis of indicator color changes (advanced. If the chief stewart tasted these liquids, though, he would not comment to the groom that he had saved the best wine for last!)

Friday, January 30, 2009

Introducing Science Saturday

I am starting a new project here called Science Saturday. On Saturday I will post a science experiment for you to try out during the week.

Blog about your experience and leave a comment on the Science Saturday blog entry for that experiment. Include a link to your blog entry for others to see.

I hope this will encourage homeschoolers to explore more science and have a lot of fun!

Friday, January 23, 2009

Making butter part II

We ran out of the first batch of butter we made, so I bought more cream and made some more. This time, however, I did it right.

I shook the jar until it all solidified, just like before, only this time I shook a little more. It only took a few more firm shakes, enough to move a semi-solid mass of cream, when suddenly it filled with liquid again--buttermilk!

The butter was now yellow (our last batch was white) and had the consistency of butter. It even harden in the refrigerator, which the last batch did not. And ds#3, who didn't care for the last batch, loves this one (he has discerning taste.)

I replaced the stick butter in my decorative butter dish instead of keeping it in the jar. I estimate that I got a pound out of the quart of cream, plus about a 12 oz of buttermilk.

Thursday, January 22, 2009

Skin model

We finished our first model, skin, from The Body Book. I ripped the pages out of the binder, put each in sheet protectors, and scanned what I need, and printed it out onto heavy paper. The subcutaneous (bottom) sheet is actually card stock while the other two are 28# paper. It is all held together with tape and was easy to assemble.

Each layer flips up on tape hinges. The boys enjoyed putting this together; we refer to it while reading through Blood and Guts.

We also demonstration the effectiveness of evaporation by rubbing a little isopropyl alcohol, which evaporated quickly, on one hand and water on the other. The alcohol feels much cooler.

One experiment not in the book that I want to try with the boys demonstrates that cold and wet are both sensed by the same sensors. Blindfold your subject and put something cold, but dry, on them and ask if they feel something wet...

Sunday, January 18, 2009

Snowflake pictures

It is snowing again today--big, light flakes. Inspired by In the Sparrow's Nest, I went out and took some pictures of these snowflakes. When you really take the time to observe them, like while trying to photograph them, you realize just how big they are.

The detail is amazing. You can clearly see in these photos that each has six sides and is unique. As you can see, the flakes show up best on a dark background, and you should let it get cold enough so that the flakes don't melt when they land on it. (Given that our temperatures are somewhere in the high 20's right now, it didn't take too long.)

You don't have to be as close as these photos appear; these are cropped, so at an arm's length you still get great detail.

Check out information on Wilson A. Bentley, The Snowflake Man, for more about these marvelous creations. (Thanks, Melissa!)

Saturday, January 17, 2009

Dissection for Co-op and zeroBio

I am teaching a dissection class during our short 6-week winter session for our homeschool co-op. The class is for 9 and up and I had a whopping 9 students sign up, ages 9 to 14.

Home Science Tools offers complete kits for a class like this. We decided to use the Intermediate Kit with seven specimens, pictured here.

The dissection guides will lead even the most novice of students through the process, including small black-and-white photos of the anatomy. I am there to clarify things, help with technique, put each specimen into a classification perspective, and often giving comparisons to human anatomy.

Our kits had not arrived in time for our first class, so I took the time to go over the tools in a dissection kit (my own.) Next I did a quick search for dissection videos and came across zeroBio, a great interactive site with some dissection videos and a lot of other resources.

My students really liked the videos and they prepared them for what was to come. This week they all enthusiastically dissected their earthworms and are looking forward to next week. They're a great bunch!

Sunday, January 11, 2009

New! Hands On Homeschool Blog Carnival

My friend, Cheryl, over at Talking to Myself has created a new blog carnival that should be a great resource for homeschoolers.

Hands On Homeschool Blog Carnival is the place to post or view great homeschool learning projects. I am always looking for more hands-on activities so I can't wait to see the submissions. The first edition is scheduled to post on February 2nd, so please drop by to submit an entry or browse the carnival!

Friday, January 9, 2009

A New Game Favorite With A Science Theme

So maybe your kids will learn more geography than science from this game; still its science theme could lead to some interesting science and math rabbit trails. And it's a great game.

See my full review of Pandemic at Games for Homeschoolers. I was never a fan of cooperative games because they never really had much gaming aspect to them. This one is clearly different and is considered by many to be one of the best cooperative games out there.

Thursday, January 8, 2009

Making butter

When my kids and I were exploring we watched the free video about making your own butter. The kids of course were all for trying this at home. I bought cream from the local dairy farm where I buy my milk. Their heavy cream is so thick you have to squeeze the bottle to get it to come out!

This was during our 6 day power outage, so even though it sat on the counter for, well, probably 2 days it still smelled fresh (maybe because our house was a bit less than 60 F?) No matter, I put it into two jars and shook them.

Sure enough, butter was made. But this cream was so thick (how thick was it?) that no buttermilk remained. It all turned to wonderful butter with a spreadable, whipped consistency. Considering I bought a quart of cream for around $3.50 and got around 2lbs of butter, this is quite economical!
The first thing I did when we got power back was to make a loaf of our favorite oat bread to enjoy with the butter. Thanks Mr. Krampf!

Wednesday, January 7, 2009

Robert Krampf is a wonderful science gem. You will find not only experiments, but great videos, too. These are not the fast, flashy, gross, loud, or otherwise more-noise-than-science type videos. They're informative, interesting, and funny! He does not in any way water down concepts, yet he does not dry them out, either.

While you do need to pay $20 for an annual subscription he has a lot of free material as well, including some of the videos. You can subscribe to his weekly experiment newsletter, too, and view a long list of experiment ideas. I find it well worth the money.