Posts Tagged ‘ chemistry for kids ’

Science Experiments: Red Cabbage Indicator (Fun for Ages 4 and Up!)

Monday, November 5th, 2012

We did a lot of Montessori science when the older kids were little, so this is an experiment we did years ago. Now the older kids are studying chemistry and ED is the perfect age (4) to enjoy the action of this experiment. Using red cabbage juice as the indicator, you add various household ingredients and compare it to an acid-base chart to see where that particular item falls on the scale.

Before we did the experiment, we read a couple of chapters from Real Science 4 Kids, Chemistry that talked about the differences between acids and bases. (See the picture below, right. You can visit their site for a preview of the student textbook. We don’t have the other materials such as the teacher’s manual, but I really love and highly recommend the textbooks.) I love the cute illustrations that show the bonds between atoms as linked arms. After finishing our reading, I told the kids to write a quick page for their science notebook that shows that bases (often) have an OH group and acids have an H group:

 

Then we went into the kitchen to explore which household items were acids and which were bases.

First we cut up red cabbage and placed it in a saucepan with water, brought it to a boil, turned off the heat and let it sit for a number of hours.

Then we strained out the cabbage and poured the juice into test tubes.

We had a huge selection of items to test — partly because there are three kids who all want to take part in the action. If I had to narrow down the selection I would recommend

  • vinegar
  • Diet Coke
  • baking soda
  • glass cleaner
  • apple (but let it soak overnight before really assessing the results)
  • hydrogen peroxide (because it bleaches the color out)

Here was our setup:

Before we started adding the ingredients to the test tube, I had the kids decide together which they thought were acids and which were bases.

After adding all the ingredients to the test tubes and labeling them, we looked for the top two most acidic items and the top two bases.

Just so you know, we found the results easier to determine after adding some water to the test tubes because I had let the cabbage sit on the stove for a long, long time and the indicator was quite strong.

You can find the acid-base color chart at Surfing Scientist (page 13) or just google “acid base color indicator chart.”

We used plastic test tubes that we got from Oriental Trading a while back, but of course you can use disposable plastic cups, baby food jars or whatever you have on hand. This was our set up a few years ago:

You can freeze the red cabbage juice for later use.

I put this into a pdf if you’d like to print out my explanation/directions for this experiment.

Making Red Cabbage Acid-Base Indicator

Another wonderful resource is the Surfing Scientist which has much more detail about this experiment.

You might also be interested in these posts from our chemistry unit:

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Building Molecules Chemistry Activity

Friday, October 12th, 2012

We moved on from talking about atoms to talking about molecules and chemical bonds. Since my kids are pretty young, this is just a basic introduction to how bonds are formed and made.

 Building Molecules Worksheet:

The screen shot below shows 2 of 3 pages.

We spent several days building different kinds of molecules:

On the first day we built water, oxygen, hydrogen and hydrogen peroxide:

The next day the kids built carbon dioxide, chlorine, ammonia and acetylene gas:

And on the last day they built methane gas, ethylene gas, methanol (wood alcohol), propane gas,  nitrous oxide (laughing gas), vinegar and others:

We used EIN-O’s molecule kit. It doesn’t have the best reviews on Amazon, but it was just fine for our needs. It comes with double-bonds (see the red oxygen molecule above) as well as the plain single bond pieces. It is a bit confusing that there would be more than one hole on the hydrogen (white balls), but I just told the kids that was how the balls were made and they were fine with that explanation.

Again, if you’re interested in building the molecules we did you can download the worksheet I made by clicking on this link–Building Molecules Worksheet.

You might also be interested in these posts from our chemistry unit:

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Chemistry: Molecule Movement Experiment and Chemistry Review Worksheet

Thursday, October 4th, 2012

We’ve been covering the states of matter, atoms and molecules in chemistry. I wanted review some of the information we’ve covered and made some basic worksheets for the kids. First, we went over the three states of matter and looked closely again at the parts of an atom.

Molecule Movement Experiment: Then we did a simple experiment with water to show that water molecules can move at different rates. We took a glass of very chilled, cold water; a glass of hot (near boiling water); and a glass that had frozen ice.  We placed one drop of dye in each glass and observed:

Below is a picture of the review worksheet I made for the kids.

You can download the chemistry review worksheet on the states of matter, atoms and molecules here:

For some reason the images of the text boxes faded away in the screen shots, though it looks just fine in the file.  This gives you an idea of what we covered in our review. I also included all the answers, but didn’t take screenshots of those.

If you want to see some of the hands-on activities and experiments we’ve done so far in chemistry visit this chemistry unit page.

You might also be interested in these posts from our chemistry unit:

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Chemistry Unit: The Size of Atoms

Monday, September 17th, 2012

We started our chemistry unit a couple weeks ago.  We’re doing lots of reading and really enjoying the books in the NOEO curriculum.

We loved, What’s Smaller Than a Pygmy Shrew? It takes a look at protozoa, bacterium, molecules and atoms — even talking about electrons, protons and neutrons. After we read through the book the kids drew pictures of protozoa. (LD’s picture is on the left, DD’s is on the right)

And on another day (after reading selections of the book again) drew water molecules.

We then turned to Real Science 4 Kids and read a number of chapters from pre-level 1. LD (age 9) complains that it is too easy for him and he’s anxious to jump into level 1. I love the cute drawings. This book explains chemistry in a way DD can really understand!

We did an activity that explains how truly small atoms are.  We took a strip of paper and cut it in half. We compared it to our hand. Then the next piece we determined was about the length of our ear or finger. Then we cut that in half. We continued cutting each strip in half (and laying one piece down) again and again until we could cut no farther.  We got up to about 9 cuts before the paper was too small.

We looked at a chart that shows how many cuts it would get to be

  • in the microscopic range (12 cuts)
  • the width of paper (14 cuts)
  • the size of bacteria (18 cuts)
  • the size of visible light waves (19 cuts)
  • electron microscope range/membranes (24 cuts)
  • the size of an atom (31 cuts)

After that the kids spent lots of time exploring an amazing website called The Size of the Universe. You can scroll in to go smaller and smaller (even smaller than atoms, electrons, and quarks) all the way out to the planets, solar system and universe.  You can click on each item and there’s an explanation of what it is.  And there’s a feature where you can mute the music (in the right hand corner) if you spend more than 10 minutes on it!

For more great chemistry ideas, be sure to visit the Molecularium Teacher’s Guide (K-4) and Molecules to the Max (Grades 5-8) Educator’s Resource Guide.

You might also be interested in these posts from our chemistry unit:

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