Posts Tagged ‘bananas’

Program 44: Playing with our Food…

September 23, 2015

Okay. Sometimes, my G3 programs come together in very interesting ways. My idea for this program started with a beautiful banana. As some of you may recall, I’m a big banana fan – they are just so darn interesting! And then it grew from there. There are so many fun science projects and demonstrations you can do with food that I just couldn’t help myself. So for our first G3 program this Fall, I had our G3 scientists take on the following:

  1. We investigated to see if TOTAL brand cereal uses real iron in its cereal flakes. [“Eating Nails for Breakfast”]
  2. For fun, I challenged the scientists to pull a table cloth out from under a full table setting…and explain to me the science behind the results [“Tablecloth Trick”]
  3. I had the scientists work hard for their afternoon snack by making their own butter.
  4. I demonstrated how the magical banana can actually form the base for a very delicious “ice cream” treat.
  5. Finally, I let our scientists combine their love of science with their creative sides by tattooing bananas with fun images and talking about how the heck that’s even possible!

EXPERIMENT #1:  “Eating Nails for Breakfast” [from Steve Spangler]

Materials:

  • TOTAL brand cereal [enough so that each scientist can have a sandwich bag filled about 1/3 of the way up – for my group of 22 or so scientists, I used 1-2 full-sized boxes of cereal. I chose to pre-fill baggies with the cereal]
  • Water for each scientist [I just distributed a standard water bottle to each scientist, though they only used a small portion of the bottle]
  • Sandwich bags that zip closed [2 per scientist]
  • Strong magnets [I actually own a nice neodymium magnet that I picked up from the Steve Spangler store…and that worked best for us as a group. But I have seen the experiment work with bar magnets, and according to its packaging, my cow magnet should also have worked well. If you have enough magnets to distribute around, all the better. I passed my one neodymium magnet around from table to table…]

The trick with this experiment is that it actually takes some time to complete it and get to the results phase. So I started our program hour with Part One of this project, and we returned to it before the scientists had to go home at the end of the program hour.

home_box_newAfter explaining to the group that we were going to try and verify that Total cereal adds actual iron to its cereal flakes, I distributed the pre-filled baggies of Total cereal to each scientist and asked them to seal up the bag (getting as much air out of the bag as possible) and smash the cereal into small pieces/crumbs. As you can imagine, my crew had a LOT of fun pounding their cereal into smithereens. After a few minutes, I asked each scientist to pour their cereal crumbs into a second, empty baggie and then fill the bag about 1/3-1/2 up with water. [I discovered during my own early testing that the process of crushing the cereal flakes created some small holes/tears in the original baggie…which of course made for quite a mess when I added water to the bag. My simple solution was to have every scientist start with a fresh bag before we added the water.] Once the water was added, it was time to set this project aside for at least 30 minutes. Truthfully, you might have luck returning sooner than that, but it’s better to be safe than sorry!

nails_breakfastWhen we came back to this experiment at the end of the hour, the next steps were very simple in deed. I asked each scientist to shake their bag of water-logged cereal flakes…which essentially breaks up the flakes even further so you get something that looks rather like a cereal slurry. If any of the scientists seemed to have a little too much air in their bag, I helped them to carefully get some of that extra air out and then reseal the bag. Each scientist then laid their bag of slurry flat on the table surface and everyone took turns pressing the neodymium magnet directly onto their bag. When you do that, the magnet pulls literal iron filings up from the slurry to the surface of the bag. You can even drag them around the top of the bag with the magnet’s help! Our scientists (and their parents!) were amazed to find actual iron in a breakfast cereal!

In the video below, Steve Spangler does a great job of explaining the experiment itself. In the 2015 National Geographic Kids book, Edible Science, there’s also a wonderful description of the same experiment (pg. 18) along with an explanation for why the heck manufacturers put iron in our cereal:

Iron is naturally found in meat and some vegetables. In those foods, the iron exists as one part of a large molecule, such as hemoglobin. However, the easiest way for a food manufacturer to increase the iron content of a product is to add pure, metallic iron. Many cereal makers grind iron into metal dust and mix it into the batter for their flakes… (pg. 18)

DEMONSTRATION #1: “The Tablecloth Trick[From Steve Spangler]

Materials:

  • I used an actual Tablecloth Trick demonstration pack from Steve Spangler that included the special tablecloth and a full table setting (plastic plate, plastic bowl, plastic cup, fork, knife, and spoon)

table-experimentHonestly, I did this demonstration because I knew the kids would have fun with this challenge. This was one of my take-homes from my Steve Spangler conference in July 🙂 I simply challenged my scientists to pull the tablecloth out from under the full table setting. I demonstrated first, and then without giving any tips or instructions, I asked the scientists to line up next to the table where I had set up the tablecloth and give it their best shots…with a promise that we would talk about the “science” behind the demonstration after they had all had a turn.

If you go to the first link above, Steve Spangler’s web site does a great job explaining how to best set up the demonstration…and what the science behind the trick actually is. Basically, you need to:

  • Spread the tablecloth out onto a flat tabletop with about 2 feet of the tablecloth on the table. Make sure there are no wrinkles.
  • Place the cups, plates and utensils on top of the tablecloth relatively close to the edge of the cloth (increases the chance of success for beginners).
  • The trick is to grab the ends of the tablecloth with both hands and quickly pull the cloth straight down and away from the table. The key is the quick, downward motion – almost like you’re whipping or yanking the cloth away. Keep saying to yourself, “Pull down… not out.” Make sure to pull perpendicular to the table and not at an inclined angle.

Amazingly, I think all but 1 of my 22 scientists were able to successfully do this trick in the first go! What is the science involved in this trick? Inertia and Friction. According to Sir Isaac Newton’s Law of Motion: 1) an object will remain at rest until a force acts on it, and 2) an object in motion will remain in motion unless a force acts on it. Thus, our full table setting (plates and silverware) will remain in place (at rest) unless a significant force acts on them. Where does the Friction come into play? Well, initially, all of the objects (the plate, bowl, cup, utensils) are at rest (not moving). When you pull the cloth, friction acts on the objects in the direction of the pull for a short time. But the tablecloth (with no hem or edging) is slippery, so these forces are small and the cloth sneaks out from underneath the objects.

EXPERIMENT #2: Snack Time…Let’s Make Butter!

Materials

  • Heavy whipping cream (room temperature – out of the fridge for 6-8 hours)
  • Small containers with secure lids (In the past I used recycled 4 oz. baby food jars, one for each scientist. This time I used small mini cups…and they worked SO much better!)
  • A little salt for flavoring
  • Bread, for snacking
  • Plates to put the snack on 🙂

Even having done this before with a different group of scientists, I’m still amazed at how easy this is…and how satisfying. There’s something really nifty about letting my scientists make something that they can instantly use (or consume). I passed out the mini cups, which had about 1/4 to 1/2 inch of heavy cream in the bottom. [This small amount of cream produces plenty of butter for each individual scientist, approximately 1-2 servings.] I instructed my scientists to add a pinch of salt for flavoring if they wanted (most of us eat salted butter at the dinner table). We sealed the cups tight, and then it was just a question of some time and arm muscle. You need to shake the cream in the container for about 10 minutes to instigate the physical change in the cream. Basically, when you agitate the cream for a long enough period of time, you are helping to separate the fat solids from the “butter milk.” [NOTE: Leaving the cream at room temperature for a while helps the physical transformation along at a quicker rate.] Every one of the scientists saw the full physical change and achieved both the full butter solids and the butter milk! And everyone loved the flavor of their butter on the bread I passed out to all 🙂

DEMONSTRATION #2:  Banana “Ice Cream”

Pages-from-Nom-Nom-Paleo-50-Page-Preview-51-785x1024While my scientists munched away on their bread and butter, this seemed like the perfect time to give them a little something sweet to sample at the end of our snacking. I recently discovered – while browsing through my Nam Nam Paleo cookbook, that you can make the most amazing fake ice cream using frozen bananas as your base.

Ingredients

  • 3 bananas (halved, placed in freezer bags, and frozen overnight)
  • 1 cup of frozen strawberries (you could probably use any frozen fruit here)
  • 1/2 cup of coconut cream (you can find that in most food stores in the aisle where they sell the fixings for adult cocktails)
  • 1 tsp. vanilla extract
  • A nice food processor

I carted my food processor in from home, and then proceeded to demonstrate to my scientists how to put together this recipe. After just a few minutes in the food processor, the ingredients really do have the texture and temperature of a nice soft-serve ice cream without using any milk or cream! The hero in this recipe is the banana. Bananas have high levels of pectins (a type of water-soluble fiber). To be frank, I don’t even understand the full “how does it really work” with this recipe. But there’s something that happens when you freeze the bananas and break up that fiber in the food processor that makes for fake ice cream magic (yum!). I had the scientists line up, and I gave them all a sample in a mini cup (like the ones we used to make butter). All of my scientists loved this recipe so much they came back for seconds…and all of the moms present seemed very interested in jotting down the recipe 🙂

ART/SCIENCE PROJECT:  Tattooing Bananas

Materials:

  • 1 banana per scientist
  • Fun images for the scientists to use as templates
  • Scotch tape
  • Push pins or toothpicks (I found that push pins worked easiest, but I know some folks would prefer toothpicks if they plan on eating the bananas later)

Olaf_from_Disney's_Frozen 254-batman-logoenhancedThis banana project was literally the starting point for this entire ‘fun with food’ program. I was DYING to try this out with some of my regulars at the library. So easy, and such a quick reward for your efforts. This one did take a little pre-work on my end, though. I selected some fun images that I thought the scientists would have fun working with: Beeker, a Minion, Olaf, a Lego Ninjago, the Batman symbol, etc. I then measured my typical banana and created a rough outline in a blank PowerPoint document (about 2 inches by 7 inches) and then sized the images to be approximately that size. [I wanted to ensure that the images I passed out to the scientists would roughly fit along one side of their bananas, and wouldn’t be too large or too small.]

After distributing the bananas, I instructed the scientists to cut out the image of their choice. No need for precision here – you want there to be a wide border around the image itself. I then had them tape the image in place on their banana. And then it’s just a question of a little time and patience. You use the push pin to punch holes around the ouline/lines of the image (like tracing the image with a series of dots). When you think you’ve put holes in all of the major lines, you can remove the paper and then just fill in some of the lines with more dots to make for more solid lines (think of it like connecting-the-dots).

Minion Banana

Minion Banana

LEGO Ninjago Banana

LEGO Ninjago Banana

Almost instantly, the dots create a brown discoloration on the surface of the banana. This happens because of oxidation. Bananas contain polyphenol oxidase and other iron-containing chemicals which react with the oxygen in the air when the cells are cut open (similar to what happens when rust forms on a piece of metal). We had some pretty terrific art come out of this science demonstration/project, and as a bonus, the scientists could take the bananas home and eat them later! The push pins actually don’t push very far beyond the skin of the banana, so 1) the bananas stay fresh for a while, and 2) the artwork on the skin remains just as lovely a day two after you complete it.

CONCLUSION

As you can see, we had a lot on our ‘plates’ for this first program (ha ha), but it was tons of fun for all! Who doesn’t love playing with their food, right?… 🙂

nd

Program 28: Banana DNA

December 18, 2013

For our final program of 2013, I wanted us to dig deep into science. That’s right – I broke out the test tubes and magnifying glasses and even some pipettes! This month we revisited one of my favorite programs from the past: Banana DNA. Our G3 scientists learned how to extract actual DNA from bananas!

dnaAs always, the program kicked off with a brief discussion. We talked about the nature of DNA itself. Do humans have anything in common with a rhinoceros? Or a frog? Or even a tree?  The answer to all questions was YES. All life forms contain DNA, which determines what that life will look like and more. In the case of our bananas, the DNA is what tells the banana to be a certain color, or a certain shape, or a certain flavor. We watched some great videos from Dole about what goes into harvesting and shipping all of their bananas. [Video 1: Dole Banana Development & Care; Video 2: Dole Harvesting Bananas.]  I also pointed out a sheet of fun banana facts that each scientist could take home with them.

Cavendish Banana...soon to be extinct?

Cavendish Banana…soon to be extinct?

One very interesting thing we discussed is the fact that most Americans eat only one type of banana: the Cavendish. And due to a fungus that is attacking Cavendish banana plants around the world, in 5 or 10 years the Cavendish banana could very well become extinct! When that happens, we will all be forced to begin eating a completely different kind of banana. Our G3 scientists’ children or grandchildren may never know what a Cavendish banana tastes like! Though this isn’t the first time a banana species has become extinct. Prior to 1950, most Americans would have been eating a banana called the “Gros Michel,” but a fungus made that banana species extinct before any of our young scientists (and maybe even their parents) were born!

OUR EXPERIMENT

Using the instructions from the magazine Scientific American as a guide, the G3 scientists discovered that we can extract the actual DNA from bananas using a few household items like dish soap, salt, rubbing alcohol…and of course bananas! I made a few tiny modifications based on experience that I’ll note below.

Our supplies for the day:

  • 1 ripe banana per scientist
  • 1/2 cup of distilled water
  • 1 resealable zip-top bag
  • 1 tsp. salt
  • 1/2 tsp. liquid dish washing soap (any kind)
  • Isopropyl alcohol (rubbing alcohol) (chilled in the freezer)
  • 1 coffee filter
  • 1 narrow and clear glass or test tube
  • 1 narrow wooden coffee stirrer

The first step was mashing up the bananas…something that we all enjoyed 🙂 Each scientist was given a whole banana sealed in a zip-top plastic bag. The goal was to achieve a “pudding” consistency. Both tracks did a great job of firmly, but gently, breaking apart all of their banana lumps and creating a bag of banana mush.

In a separate cup, we combined 1 tsp. salt and 1/2 cup of distilled water, stirring until the salt was dissolved. This salt water was then added to our banana “slurry,” gently kneading to combine the ingredients in the bag. We then added 1/2 tsp. of liquid dish soap to the “slurry,” again gently kneading to combine the ingredients.  This led us to our trickiest step:  straining our banana slurry (to collect just the banana liquid in a cup). [The soap actually helps to dissolve the membranes of the cell walls that hold the DNA, and the salt helps to draw the DNA strands toward each other.]

Photo Dec 05, 4 46 48 PMI made some modifications to our previous work with banana DNA (and to the steps as identified by sites like Scientific American) to help with our success. Each scientist placed a coffee filter in a clear plastic cup, holding it in place with a rubber band. [This was an important and successful improvement to the process! In the past, so many of our filters fell back into the cup forcing the slurry to be restrained time and again.] Once we had maybe 1/4-1/2 inch of banana liquid in the bottom of our cups, each scientist carefully worked with a partner to remove the filter and remaining slurry from the top of the cup so that all that remained was the strained liquid beneath. Using pipettes, the G3 scientists then filled their test tubes about 1/2 way up with the banana liquid. They then used a clean pipette to add chilled isopropyl alcohol to the top of the test tube. [NOTE:  You can keep the alcohol in the freezer…it will stay in liquid form!]

The online experiment descriptions say you may have to wait up to 8 minutes to see some results, but almost all of our G3 scientists had immediate and successful results in hand. All G3 scientists were able to extract the white, fibrous, web-like DNA from their bananas! We tried out best to preserve the DNA bits in plastic baggies for those scientists that wanted a souvenir, but I think that photographs are the best way to preserve the results of this experiment. Check out the nifty slide show below of our scientists (from both tracks) in action:

In a final note, many of the banana facts I shared were obtained from the Chiquita banana web site.

I’m looking forward to seeing everyone in 2014 when our next programs will start. Happy holidays!

G3 Program 2: BANANA DNA

January 30, 2012

Our supplies

For our second program, G3 focused on being true lab scientists by learning how to extract actual DNA from bananas!  The program kicked off with a brief discussion about DNA itself. Do humans have anything in common with a rhinoceros? Or a frog? Or even a tree?  The answer to all questions was YES. All life forms contain DNA, which determines what that life will look like and more. In the case of our bananas, the DNA is what tells the banana to be a certain color, or a certain shape, or a certain flavor. Following the instructions from the magazine Scientific American, the G3 scientists discovered that we can extract the actual DNA from bananas using a few household items like dish soap, salt, rubbing alcohol…and of course bananas!

The first step was mashing up the bananas…something that we all enjoyed 🙂 The G3 crew described the bananas, or the banana “slurry” as “just plain gross,” “brownish,” and “looks like vomit.”

Mash those bananas!

Yuck!

We then added salt water to the mush, followed by standard dish washing soap, and then we were ready to strain our banana slurry (to collect just the liquid in a cup). [The soap actually helps to dissolve the membranes of the cell walls that hold the DNA, and the salt helps to draw the DNA strands toward each other.]

Surprisingly tricky step

The filtering step proved unexpectedly challenging as more than one of our scientists accidentally dropped the banana filter and banana chunks into the cup that contained the strained liquid. Some scientists even had to restrain 2 or 3 times! But we all collected enough liquid to add to our test tubes. The final step was adding a top layer of rubbing alcohol to the test tubes (Head G3 scientist Nicole helped with this part). And then we just needed to wait with fingers crossed to see if we had good results.

G3 scientists hard at work

While we were waiting, Nicole pointed out the sheet of fun banana facts that each scientist received at the start of the program. In particular, we talked about the fact that most Americans eat only one type of banana: the Cavendish. And due to a fungus that is attacking Cavendish banana plants around the world, in 5 or 10 years the Cavendish banana could very well become extinct! When that happens, we will all be forced to begin eating a completely different kind of banana.

Success!

The ring of white, web-like stuff is billions of strands of banana DNA

The results started pouring in after only 5 minutes…and every one of the G3 scientists successfully extracted banana DNA! [It should be noted that it even took Nicole multiple practice runs to extract the DNA herself, so clearly our program is full of super star scientists 🙂 ]. Our G3 scientists described the DNA as “white,” “web-like,” and even like a loose collection of “snowflakes.” Of course, many of the scientists wanted to take home their DNA. Coffee stirrers were passed around so that each scientist could scoop out their extracted DNA and place it in a zip-top baggie to take home.

At the close of the program, activity sheets were passed out to all. Each scientist was also able to take home a copy of the experiment instructions, as well as the sheet of fun facts about bananas. Many of the banana facts were obtained from the Chiquita banana web site. I wonder what we’ll be doing next!…