Monday, May 19, 2008
Does heat or time change the starch content of food?
Chapter 8 in the Chemistry Level I text discusses energy molecules, including starches. The corresponding Laboratory Manual experiment uses iodine to test for color changes that vary by the food being tested and the “control” starch sample. But does time or heat change the presence of starch within certain foods?
The variations suggested below will allow your students to observe if the process of cooking or over-ripening has an effect on starch content.
I. Think and discuss.
Students should create new “objectives” and “hypotheses” for the materials to be tested after reading the variations suggested below.
II. Observe it.
A. Set up the experiment “control” as you did for the original Lab Manual experiment.
B. Now, drop the iodine some fruit that has become overly ripe. Do you get the same result if you drop iodine on fruit that is not yet ripe?
C. What happens if you drop iodine on baked potatoes or boiled potatoes or cooked carrots?
III. What happened?
Have your students add any of these varied foods that they test to their Results list in their Lab Manual and record the color changes (if any).
IV. What next?
Are there conclusions the students can draw from their experiments? Make sure to be factual and specific so they are valid conclusions.
Can they apply what they are learning about separating color mixtures to how colors can be combined in art? Help them see how chromatography in science is interrelated to pigments made for use in art and how they can make even more color mixtures when they paint or color.
What did you find to be the most interesting observations made by your student? Did any of the questions or conclusions surprise you? Do you feel he or she is making a connection with how science affects every part of our modern life? Feel free to send us a response with the most interesting entries in their Lab book or your comments about what impact these experiments have.
Posted by Rebecca W. Keller on 05/19 at 04:55 PM
Tuesday, April 22, 2008
Vinegar and Ammonia in the Balance
Experiment 5 in the Chemistry Level I Laboratory Manual takes a look at chemical balance and the effects of chemical concentration and proportion through the use of vinegar (an acid) and ammonia (a base). Titration is introduced as an experimentation technique: small changes can be observed when a second chemical is added in small amounts incrementally.
Here are more variations that can be used to ask the "What if?" questions which build critical thinking skills as students are asked to apply what was learned in the Laboratory Manual experiment to these additional variations.
I. Think and discuss.
First, discuss with your students what they anticipate will happen with each variation below.
II. Observe it.
Try any or all of these variations:
A. If you use only half the vinegar, do you need only half of the ammonia to achieve the same reactions?
B. If you double the vinegar, do you need to double the ammonia to get the color-change result?
C. Does the reaction change if the solutions are heated? If they are cooled?
III. What happened?
Have the students write about what happened in the Results and Conclusions sections of their Lab Manual and also make a new graph that can be compared to the original experiment graph. Observe how organizing experiment data into graphs now makes comparing results easier visually.
IV. What next?
Discuss how chemical concentration affects items you use around the house, such as concentrated liquid laundry detergent or the floor cleaner which says you must dilute it with water in a pail in order to use it.
What did you find to be the most interesting observations made by your student? Did any of the questions or conclusions surprise you? Do you feel he or she is making a connection with how science affects every part of our modern life? Feel free to send us a response with the most interesting entries in their Lab book or your comments about what impact these experiments have.
-----
Posted by Rebecca W. Keller on 04/22 at 05:37 PM
Monday, April 14, 2008
Testing for pH relates science to household staples
With this entry, let's add to our "What if?" questioning with "What's in it?" When students begin to understand how chemistry relates to the foods we eat and solutions we use around the house, it brings "science" into their everyday lives.
Let's look at some variations for Experiment 4 in the Chemistry Level I Laboratory Manual. That experiment describes how we can create our own acid indicator paper strips. It then guides us through testing various acid and base liquids. Here are a few more ideas for liquids that can be tested and that we consume or use on a regular basis.
In addition to having your student record experiment results in the Results and Conclusions sections of the Laboratory Manual, let's use our critical thinking skills process to add even more depth:
I. Think and discuss.
First, discuss with your students what they think will happen with each variation (below) that will be tested.
II. Observe it.
Use the acid indicator paper strips to test the following questions:
1. Is there any difference in pH between a clear soda (citrus such as Sprite®) and a dark soda (cola such as Coke®)?
2. Is there any difference between balsamic vinegar, wine vinegar, apple cider vinegar, or another vinegar?
3. Is the any difference between window cleaner and ammonia?
4. What is the pH of different waters: bottled water, mineral water, tap water?
III. What happened?
Have the students write about what happened in the Results and Conclusions sections of their Lab Manual but also discuss how the results they are seeing relate to the purpose of the various liquids. For example, among the sodas or vinegars, how does having a higher or lower acidity affect the taste?
IV. What next?
Have students ask their own "What is in it?" questions. Ammonia is the "control base" in the lab experiment: Is it in other kinds of products around the house? Are they similar in the ways they are used?
What did you find to be the most interesting observations made by your student? Did any of the questions or conclusions surprise you? Do you feel he or she is making a connection with how science affects every part of our modern life? Feel free to send us a response with the most interesting entries in their Lab book or your comments about what impact these experiments have.
-----
Posted by Rebecca W. Keller on 04/14 at 08:12 AM
Thursday, April 10, 2008
Science began when humankind first asked "Why?" and then went to look for an answer. We believe "why" and "what if" are still the most important words anyone can use when studying science at any level.
This blog will pose new questions, many linked to specific RS4K lessons or experiments, that may help you and your student(s) further enjoy the discovery that is science. Learning to ask questions that go beyond information presented helps promote discernment, analysis and evaluation skills – known as "critical thinking“ – across all areas of study.
Asking "What if?" trains our minds to understand experiments in more depth and teaches us to think for ourselves beyond information presented.
For example, Experiment 3 in the Chemistry Level I workbook asks students to identify chemical reactions using a variety of household products. What if...your student first warmed the vinegar before adding the baking soda?
Here is a good process to use when you want to open any experiment to new possibilities.
I. Think and discuss.
Have students first discuss what they think would happen if the vinegar was warmed before adding the baking soda. Direct their inquiry with questions. Do they think the reaction will go faster? Slower? Stop?
II. Observe it.
Have the students slightly warm the vinegar in Experiment 3 by placing the measuring cup in warm water and then proceed with the experiment.
III. What happened?
Have the students write about what happened when the vinegar was warmed.
IV. What next?
Have students ask their own "What if?" questions. What if the vinegar is very cold from the refrigerator? What if it is diluted with a bit of water?
Did this process of inquiry make the experiment more educational? Did your students feel more involved because they could ask their own questions and then find the answers? Did anyone come up with a surprising or creative question? Do you see other areas of study where this scientific process of inquiry would be useful?
-----
Posted by Rebecca W. Keller on 04/10 at 02:44 PM
