Friday, January 8, 2010

Testing for Starch

In Cranberry Thanksgiving, Mr. Horace, the city man, is dressed nicely in starched clothing. So, one of the lessons talks about starch and how it can be used in laundry, but also how you can test for starch with iodine. The Fold n Learn has a little data sheet to use for the experiment, but in the end I couldn't use it. This science teacher needs big action when it comes to an experiment! So, as every good scientist does, I broke out the Styrofoam egg carton. I filled it with bunches of kitchen items so we could test for the presence of starch.

I bet you're curious as to what we have here:
  • bread
  • potato
  • sugar
  • flour
  • Old Bay- just to get our Maryland on
  • cornstarch
  • egg shell
  • carrot
  • rice
  • cooked spaghetti- I raided the trash because I'm that kind of homeschooling mom...
  • green bean
  • liquid sizing from our laundry area- works like starch without the stiffness (according to the can- honestly I would not know what to do with it and Dan will concur)
All set up- good science is about to happen. Can you feel it?

For the experiment, you will need medicinal iodine. You can find it in your pharmacy. Typically, iodine is found in solution. It's a rusty color. We also have a disposable pipette.

We are underway! J4 takes a turn. I taught the kids proper pipette technique and they put a few drops on each item in the egg carton well. We watched for a color change. Look in the lower left corner of the picture below to see J4's data chart- he filled the whole page with circles and stuff inside. He didn't want to be left out!

I had the kids make their own data charts. They had to draw the circles to be the wells and they drew what was inside and labeled it. I like to have my kids make their own data charts because it helps them to learn how to organize information. I one hands a real scientist a data chart every time he/she goes to investigate something. They used colored pencils to color the item it's original color before we started.
All done! I let all of them have a turn using the pipette and we talked about the results. Which ones turned color (iodine turns purple/black in the presence of starch) and which ones didn't. Some turned quickly and some didn't. And it turns out that Magic Sizing has no starch in it. Crazy, huh? We did do some predicting ahead of time because that's what scientists do. The kids correctly picked out the veggies/grains that had starch so we are doing something right in the area of nutritional instruction.

Finished data chart- I had them show an after iodine picture as well and they had to make statements about what they observed. We added this to the lapbook and I made a color copy to go with our study on chemical and physical changes which we'll doing early next week.
What's fun too is to discuss chemical indicators. Iodine is a good indicator for starch. Cabbage juice is a good indicator for acids and bases. I mean really good. That's another fun experiment.

E11 did a Daily Quest on iodine yesterday using Web Elements. Iodine is a halogen found on the next to last column of the Periodic Table. Check out the contact explosive video. Dan actually made something in his lab that did the same thing. Iodine is pretty reactive and you can check out more chemistry facts yourself. I'm just sure I've peeked your interest!


Your dh said...

We made it in our college dorm room, not the lab. That is what happens when a chemical engineering student rooms with a chemistry student. Ours popped with the energy closer to snap rocks, but it was still fun!

Cindy said...

Love this! It's right up our alley!

kim wright said...

very cool!

Tristan said...

I nominated you for a blog award here:

Ticia said...

What a great idea. I love this.

MamaGames said...

This is a fabulous way to do this experiment! I love how you used an egg carton to hold all the items you wanted to test. Thanks for sharing!

Gail said...

Heather - you are just the coolest homeschool mom I know!