Macromolecules: Food Tests Lab

 My plans for Tuesday were upended.  Paul, eleven, is joining us for class.  I have a new student starting Bio Tuesday, too.  I’m postponing the lecture planned and doing food tests instead.  I scrounged through my kits and chemicals for the chemicals and food samples.  Home Science Tools has this Chemistry of Food Chemistry Kit and Food Science Projects.  I’m using this slideshow, which has most of the food tests. I keep the slideshow up on the TV so the kids can compare their results to the samples in the slideshow.   I found a small amount of Sudan III for this lipid test.  We will do the the brown bag test, too.  The Benedict’s test for sugars, such as glucose, requires the test tube to be placed in a hot water bath.  I use an electric kettle so it’s easy to heat the water for the hot water bath.  I pulled cornstarch, corn sugar, sucrose, corn syrup, gelatin, and oils.  I’m buying some chips and have beans for the kids to test.  Should be fun!

Fake Blood

No, not for Halloween!  I am planning ahead for blood testing with the Genetic lesson.  I do simulated blood tests before the kids test their blood with Eldon cards.  Usually, I buy simulated blood kits.  I’m determined to make my own kits.  Here are instructions for a cheap blood test with food dye, milk, and vinegar.  Here is an article with directions to make ion solutions.  I’m planning a modification. Type A is lead nitrate.  Type O blood is water.  Type B blood will be milk.  

I made up a 1M solution of lead nitrate and added some red food dye.  I’ll just add red dye to milk and water for Type B and Type O.  The anti-sera are ammonia for Type A, lead nitrate and vinegar for milk, Type B.  Neither ammonia nor vinegar will change water, Type O. The vinegar did not precipitate with the lead nitrate.  But, we’ll have to see how it works in lab.   I have a simulated blood type kit I bought last year on hand, too.  Once we do the lab I’ll post pix and a review.

Osmosis and Diffusion

 After the cell test, the kids completed two labs: Osmosis and Diffusion.  Here and here are the lab links for the diffusion lab.  Here are the lab instructions for the Gummy Bear Osmosis lab.  I used recycled yogurt containers instead of glass beakers.  The kids used three different colored gummy bears for three trials in each yogurt container. The kids added vinegar or sugar or salt to most of the samples.  Two groups used plain water.  

For the diffusion lab, use cheap baggies and knot them closed.  The cheap baggies work as well as dialysis tubing, which is traditionally used for this diffusion lab.  We used recycled yogurt container instead of beakers for this lab, too.  Because the yogurt containers are so large, (32oz) the kids added 60 drops of iodine instead of ten.  If you follow the directions in the lab and use smaller beakers or plastic cups, you won’t need more than 10 drops.  

The kids worked in cell concept maps, too.  Take a look.

Old Tech: Timers

 I brought out my iPods, old iPhone, and a Kindle Fire to class to use as timers.  The kids time yeast pearls in peroxide.  If the device has a clock, it probably has a timer.  If there is a spill, the device was old and used anyway.  Hold on to older tech for lab!

Enzyme Lab

Warning!  This was an ambitious lab to do with a general Biology class.  The Biology Co-op Class completed this Catalase Activity in Immobilised Yeast, a UK web site.  The kids created yeast ‘pearls’ and tested the pearls in hydrogen peroxide solutions.  It went pretty well.  I made up sodium alginate and calcium lactate solutions in advance using  this brand.  We used ordinary baker’s yeast and fresh solutions of hydrogen peroxide (3%).  The kids diluted the hydrogen peroxide and times how long for the yeast pearls to rise.  I had the kids enter their data into a Google sheet—just to review how to enter data and insert formulas.  Next time, we will discuss enzymes with this slideshow and this Scientific American article.  Yeast cells have peroxisomes.  I’m using this slideshow about peroxisomes for class.  Here is the bottom line.  Yeast cells have Peroxisome, which have catalase, an enzyme, which is a protein.  Enzymes catalyze chemical reactions, in this case, the decomposition of H2O2.  There is a great deal of science to discuss on Thursday.  Whew.  Take a look at the lab pix.

Microscope Gadget

 I bought a gadget for cell phones to capture images from light microscopes.  The gadget’s photo from Amazon is below.  I took a photo of the attachment on the microscope and an image captured with the cell phone.  It was hard to angle the cell phone to capture the image.  I’ll let the kids play with the gadget to see if they like it.  

Used Graphing Calculators

 Most of the time, I bid and buy used calculators from www.shopgoodwill.com.  I have had great luck overall.  Full disclosure: This is as close as I get to gambling. I bid on calculators which work. Once in a while, a calculator doesn’t work.  I save it and cannibalize it for parts, such as the battery cover.  Avoid calculators with a black smudge or spot.  The spot can mean there is damage to the LCD screen.  Look at several of the images on the bidding site: the image may have a shadow, not a spot on the screen.

Family Science: Resin Hair Clips

 One of the lifestyle blogs, A Beautiful Mess, has a post about How to Make Statement Hair Clips, with a Resin Kit and liquid Sculpey, a polymer clay.  Better Homes and Garden, BHG, has resin barrettes instructions, too.  Here are hair clips instructions using E6000 Craft Adhesive.  Here are instructions using polymer clay.  Ask your kids to decide what make a good hair clip?  Would it be cheaper to just buy Resin Hair Clips?  Could you make and sell hair clips profitably? See all of the lessons—even if you decide to forego making hair clips at all!

Let’s look at microscope slides.

 Update: Is this the first time your kids are using a microscope?  Get out paper money to learn how to focus the microscope.  I use inexpensive microscope slides with large specimens, such as a flea leg, or pollen, for newbies.  It’s easier to locate the specimen and focus than trying to focus on bacteria.

The kids examined microscope slides with light microscopes, digital microscopes, and a clip-on microscope.  I have samples of cork.  The term, ‘cell’, was coined by Robert Hooke when he examined cork under a microscope slide.  I have about two dozen bacterial and protozoan slides for the kids.  They made sketches, too.  I was able to do a little instruction with the light microscope, too.  I plan to have three  light microscopes available whenever we look at slides.  I ordered an inexpensive smartphone microscope adapter to try in class next time we examine slides.  

Cell Size

 Update: The kids compared surface area to volume with several different sized boxes.  I distributed M&Ms after they measured the boxes.  The assessment is an explanation of why cells are small using the surface area to volume ratio.  I used mini M&Ms, regular M&Ms and Brownie M&Ms to reinforce the idea that mini M&Ms have the greatest surface area to volume ratio, like cells.

Why are cells so small?  Here is the answer.  Cells must move food and water in and waste out.  It’s all about the surface area to volume ratio.  I’m using two activities: Candy Coated Biology and Calculation of Surface Area to Volume Ratio.  I pulled out rulers and boxes I have saved.  How do I assess activities like these?  I ask the kids to write a brief paragraph explaining why cells are small using surface area to volume.  Whenever possible, I just ask kids to explain the concept to me in class.  Kids remember nearly everything we do in class and almost nothing that I say in class.  Bring on the activities.  

Cell Structure and Function Quizzes

 While I am on the topic, I need to be sure the kids understand both the structures and respective functions of the cell.  Here, here, and here are online organelle and function quizzes.  Here is a straight-forward test with organelle function and labeling.  I like this sort of test, one without any tricks, such as ‘Which statement is false?’  I plan to use the Apologia Biology Test (Module 4 in the third edition)as review before the test in class.  I plan to ask the class to compare prokaryotes and eukaryotes and to explain the properties of the cell membrane; both are questions based on class activities or labs.  No surprises or tricks, just an assessment.

Cell Organelle Quiz

 Yes, blog posts will arrive in batches.  Next week, the Bio Co-op class has a quiz on Cell organelles.  Here is the quiz. (Scroll down this website  for answers.). Yes, it has a word bank.  Here is a more challenging version.  This quiz is a spot check to see if kids can identify organelles.

Older Tech and Microscopes

Update: I ordered a Smartphone Microscope adapter from Amazon to try.  Usually, the smartphone’s camera quality governs the image quality.  I want to try using a smart phone with a traditional, light microscope.

I’m charging an old iPhone 4 for lab Thursday.  The kids are using traditional microscopes, digital microscopes, and Clip-on Microscopes for cell phones.  I pulled out bacterial and protozoan microscope slides.  Below are a few pix to compare the resolution with the different devices.  I ordered a couple Samsung 303 c312 Chromebooks from eBay, just to use with the digital microscopes.  The clip-on microscope for the cell phone has limited resolution.  However, it’s under $5 from Walmart—due to arrive in two or three weeks.  Despite the limitations, even a clip-on microscope gives kids the experience of using a microscope.  Turn them loose to look at various objects in your house.

Apologia Biology: Pond Life Experiment

 Apologia Biology has a Pond Life Experiment.  The idea is to look at live Protozoa, algae, and bacteria in situ.  Here is the issue.  The little critters move around so much it is hard to capture an image.  (My kids look at prepared slides of Protozoa instead.)  Many families are very dedicated to following directions verbatim in the textbook.  Good for you!  If you want to look at live pond samples, use a quieting solution, methycellulose, to slow the bitty critters under the microscope.

Cell Models

 Update: I’ve been posting Cell models as the photos arrive.

Update: One student created a novel animal cell model with natural materials.  Take a look.  The same teen created a plant cell with Legos.

Next week the kids are completing Animal and Plant Cell Models.  Lacie made hers, shown below.  I’ll post more examples as they submit the models.  The kids must complete both plant and animal cell models with at least ten organelles and a key.