Fruit and Vegetable battery

Hello there. I've seen a lot of lemon battery projects, potato battery projects, etc. on Youtube, but when I tried them on my own, it seldom works the way they do on youtube, online, or in science books I've purchased. So, I tried to work out as many kinks as possible, but I still encountered some glitches. 

I've done this project in the fall of 2014, but I didn't blog about it for two reasons. Firstly, I didn't take my own photos in the classrooms. Secondly, the kids loved the experiment because it was brand new to all of them, but I found it stressful and frustrating. I was conducting the project for the first time, and I didn't know what to expect. 

Still, this one is definitely worth a try.

Supplies you need -

• pennies (anything copper is fine, too)
• galvanized nails (zinc covered)
• alligator clips (buy these at Harbor Freight, Frys, etc.)
• multi-meter (again from Harbor Freight, Frys, etc. You can get them from free from Harbor Freight with coupons.)
• assorted Resistors  > 500 ohms (Harbor Freight, Frys, or excess electronics shops)
• assorted LED's (Harbor Freight, Frys, or excess electronics shops)
• assorted fruits and vegetables 
• plastic knife
• 9 volt battery

 

The science project I've designed for the elementary school is as follows - the students need to figure out at what voltage each of the LED's (amber, red, yellow, green, and blue) light up. 

I was told that amber LED should light up at 2 volts, red LED at 3 volts, and yellow, green and blue should light up at 4 or 5, but this was not the case for me.

Summary of project instructions -

1. Create a fruit/vegetable battery by poking one nail into the one end of the fruit/vegetable and inserting a penny into the other end of the same fruit/vegetable. If the fruit/vegetable skin is tough, use the plastic knife to make an incision to insert the penny.
2. Connect an alligator clip on the nail and another on the penny.
3. Connect a multi-meter to the other side of alligator clips, measure the voltage and write it down.
4. After unclipping the alligator clips to the multi-meter, clip them to a LED and see if the LED lights up. If it does light up, write down the LED color next to the voltage.
5. Go on to the next LED. If it doesn’t light up, connect another fruit/vegetable battery to the circuit by repeating from step 1.

My classroom findings are (ranging from 2nd graders to 5th graders):

1. The alligator clips I purchased were too small for younger students.
2. The alligator clips get slippery with fruit/vegetable juice, which makes them even harder to use.
3. The LEDs I purchased (some inexpensive ones from Excess Solutions as well as some quite expensive ones from Fry's) didn't light up at expected voltages. The LEDs started lighting up ~7 volts.
4. To get 7 volts of voltage, most teams of students had to string ~10 fruits/vegetables.
5. The LEDs were supposed to light up at different voltages, but several of them lit up ~7 volts, but some of them were quite hard to see or were directional.

The LEDs didn't light up at expected voltages due to inefficiencies in the circuit. A voltage reading could be affected by how the clips were clipped to the nail or penny.

I have a 9 volt battery and assorted resistors listed in the supplies list, because if you're not sure if the LEDs are working or not, you can always test them by hooking it up to the battery.

1. Clip an alligator clip to left side of the battery and clip another alligator clip to the right side of the battery.
2. Clip one end of the resistor to one of the alligator clips.
3. Clip another alligator clip to the other end of a resistor.
4. Clip a LED between the alligator clips from the left side and the right side, making a closed loop. If the LED lights up, then LED is good. If not, go on and test another one.
5. Then use the tested LED to test your fruit and vegetable battery.

I was conducting this experiment in a 2nd grade classroom, and it was very stressful because younger students had more difficult time working with the alligator clips. Everyone was asking me to help with clipping, and there were only two adults (me and the teacher) in the classroom. I was muttering to myself that I'll never do this project again when a little girl came up to me and said, "This experiment is so awesome! I never thought you can light up a light bulb with a cucumber!"

Her team had a series of potatoes, lemons, cucumbers, etc., but that comment just made my day. She didn't see how I was stressed out because it wasn't working the way I had planned, but she only saw how neat it was to light up a LED with fruits and vegetables.

Though most students struggled to light a LED, they were very enthusiastic and really pushed themselves to get the most out of the experiment. I plan to do some variation of this project in the future; however, I'll ask for a volunteer help from each classroom.

A picture of the electronics kit I created for this project.

Again, though I was stressed out by this project, it got progressively better with each class (probably because I tossed out my worksheet and just went with the flow). Every class enjoyed this project a lot and asked me if we had another electronics experiment in out project list for this year. 

There is an experiment with conductive dough. I might give that a try soon, and let you know how it goes. In the mean time, why don't you give this one a try?

Have fun.

Fantastic Foam Bridges - March 30, 2015

I do a lot of hands-on building projects because the students seem to enjoy them the most. This project is a variation on a marshmallow bridge project. This one is really exciting for the students because there's an element of competition, which brings and urgency into the situation.

 Supplies List:

•     Foam cubes - it doesn't matter what the size is unless it's really small. 1 inch foam cubes work pretty well.
•     Toothpicks
•     Small cups to hold pennies (tiny cups you'd get from a dentist's office)
•     Paper clips
•     Pennies (up to 700 pennies)
•     Plastic tub (to catch the pennies if/when the bridge collapses)

I draw a couple of truss bridge designs on a white board and talk about the triangles in the bridge design. Then I go on to talk about the advantages of using triangle; however, I caution them about the hypotenuse. With the toothpicks, the students have to do something about the length difference.

Project Instructions:

1.     Hand out a tube of foam cubes and ~250 toothpicks to each team of students.
2.     Build whatever shape the team wants to build.
3.     Build, test, & build, again!

Here are some records to break for next year:
 
2nd graders - last year, 298 pennies
3rd graders - this year, 250 pennies
4th graders - this year, 450 pennies
5th graders - this year, 650 pennies

I don't have a lot of class pictures because I have to load the pennies very carefully, evening out the load on the bridge. So, the teachers take the pictures, but I haven't received the pictures, yet. So, here's what I have.

~150 pennies in the right and the left cups each

Try this one at home and have a wonderful time.

P.S. - The only problem with this project is that the foam cubes are quite expensive (between $17.95 - $24.95 per 102 cubes), and we can't keep reusing the foam cubes. So, it does get expensive for a class project when I try to collect $10/year/student for the science projects. If you know where I can get them cheaper, please let me know.

Eerie Eye Tricks - March 12, 2015

This project is probably more appropriate for primary grades. I do have another eyes project for intermediate grades. I'll post that later.

Supplies List:

• 6 to 8 pieces of 4in x 20in mylar (I found old calendars from RAFT and cut them into strips)
• 2 x # of students in your class egg carton bottoms (the cup side) with holes (chopstick size) randomly poked out (don't you love how technically precise I get?)
• A worksheet of up to 10 to 20 pictures of prey and predator animals (please include a picture of a baby and a Harper seal)

I start this project by talking about how the cells in our eyes are one of the oldest cells we have in our body. Then I quickly talk about cell renewal rates and the longest living cells, i.e. those that last a lifetime:

Here are some cell renewal rates of our body:

• Red blood cells (erythrocytes): 120 days
• Platelets: 10 days
• Neutrophils (a type of white blood cell): 10 days
• Fat cells (adipose cells): 8 years
• Cells of the crypts in the colon: 7 days

The longest living cells, i.e. those that last a lifetime, are:

• Neurons of the cerebral cortex 
• Cells of the eye’s inner lens
• Muscle cells of the heart

* All above info from Alaka Halder on Quora.

Then I go on to talk about why various creatures have eyes where they have - that eye location helped the creature best survive the environment in which it had to live. 

Humans have their eyes in the front. The binocular vision and depth perception are vital for an animal that swung through the trees. 

Prey animals have their eyes high and to the side of their heads. This grants them almost 360-degree view, as well as above their heads. They do have a small blind spot directly in front of their faces, but their keen sense of smell and big ears help them avoid their sight deficiency.

 Mylar Project Instructions:

1. Hand out each strip of mylar to a pair of children. 
2. Have the first child stand with a piece of mylar around his/her forehead height and bend it (not crease it, but rounded bend) to see the back of him/her.
3. The second child will stand about 15 to 20 ft behind the first child.
4. Then try to get the second child to sneak up to the first child successfully while the first child is looking into the mylar to check the safety of his/her surroundings.
5. Do this a couple of times, then swap.
6. You can do this with a group of children, and take turns until the whole class gets to try it.

*Sometimes it is quite difficult to see (for the children) if they don't get the angle right, but most should be able to do this.

I finish this section of the project with a question - would any of them like to trade their eyes for the mylar eyes (being able to see the side, top, back, etc.)? And why? You'd be amazed at what they come up with for wanting to trade or not trade their eyes. 

Egg Carton Project Instructions:

1. Hand out two egg carton bottoms with a hole poked in them to each child. 
2. Have them cover their eyes with the egg carton bottoms and see out the holes.
3. Have them try several different locations (at the same time, i.e. a hole in left side might be pointed up and a hole in right side might be pointed to the side) and ask them to talk about or write down what they see.
4.  Then I ask the children if anyone can tell me what creature has eyes like these?

I finish this section of the project with a question - would any of them like to trade their eyes for the egg carton eyes (being able to see two different locations, etc.)? And why? Again, you'd be amazed at what they come up with for wanting to trade or not trade their eyes. 

Then I go on to talk about how just by looking at the eye location, we can guess whether the animals are prey or predator animals.

Animal pictures worksheet Instructions:

1. If eyes are in the front, they belong to a predator.
2. If eyes are on the side and high on the animal's head, they belong to a prey.
3. With pictures of babies and Harper seals, the children get confused. This is another point of discussion.

Again, lower grades seem to enjoy this much more than higher grades, but I've done this with 4th and 5th grades with additional invisibility elements to the lesson. This will follow next (I'll try for next week, but I'm not sure). 

Have fun!

 

Stupendous 2015 Strawckets! - Part 2

I thought about not writing part 2 to this wonderful project, but there were too many awesome rockets from  2nd graders and 4th graders to ignore.

When I go into a classroom, I usually try to give students some context for the project  we're doing that day (what's the point if they don't understand the relevance?). For this project, I talked about the possibility of a manned mission to Mars and how we need a new rocket technology to get us there. Of course, we also need a very efficient rocket design that will make the most of the new technology. 

I also talk about what we take when we go on vacation, and what things we must take to Mars or elsewhere when it could potentially be a one-way trip after a problematic landing. Sometimes (I haven't done it recently), we have a discussion about the fact that it might cost more than $1,000,000 to take 1 pound something into space. All these problems point to coming up with a very efficient rocket design:

1. to make it safer for the astronauts
2. to arrive at the destination faster
3. to save money

 So, without farther ado, here are some great designs from today's classes.

2nd grade Distance Strawcket Winners

2nd grade Spiral Trick Strawcket Winners

Other Strawcket designs from a 2nd grade class

4th grade Distance Strawcket Winners

4th grade Spiral Trick Strawcket Winners

Please check out some other interesting designs from the 4th grade class.

Sure, a lot of these designs may have problems with aerodynamics, but I don't feel that it's my job to curtail their creativity in any way.

The words to remember for my science project classes are - curiosity, creativity, and determination.

I  hope you have fun with your strawckets.

Stupendous 2015 Strawckets! - Part 1

I usually do 10 projects in a school year (try to do a project a month for most classrooms, and do a few more for my child's classroom), and I try to mix it up so that kids and I don't get bored. BUT this is one project that I go back to every year because kids ABSOLUTELY love this project.

Before we start building our strawckets, I explain Newton's Second Law, which says  

Force = mass x acceleration (I use mass and weight interchangeably in the classrooms).

Over the years, I've learned one thing from the kids of all ages and grades - adults consistently underestimate their ability to create and problem-solve. So, I cover the Newton's Second Law in Kindergarten classes, too, but I use addition instead of multiplication, and use visual aids. What I want them to understand is the relationship between the three variables. 

If the force is constant (our lung power), then if mass goes up, then acceleration goes down. If the mass goes down, acceleration goes up.

Then I ask for volunteers and have the biggest, tallest child, the smallest, shortest child, the fastest runner, and the slowest runner come up for a demonstration. The biggest, tallest child might have stronger lung power than the smallest, shortest child. The fastest runner might have stronger lung power than the slowest runner. BUT, that's just a guess. It's not necessarily true. It all depends on how efficient the rocket design is in using the lung power. I try to have the kids think about all these factors before we build the strawckets.

Supplies List: 

• Boba straws (these are wider straws for pearl drinks served at restaurants, and Asian smoothie shops)
• 8 1/2 in x 2  3/4in strips of paper (fold a copy paper width-wise half, and then half again, giving you four pieces of  8 1/2 in x 2  3/4in strips)
• Index cards
• Scotch Tape

Building Instructions:

1. Wrap the paper around the straw and tape it down the seam. Make sure it doesn't stick to the straw, and that the straw can slide in and out easily.
2. On one end, create a cone, and put a piece of tape around it.
3. Now, put the partially built rocket on your straw and blow it. It won't fly very well.
4. Now, cut out fins from a piece of an index card and tape it on the rocket. Any place you choose.
5. Now, blow it and see how it flies. If it doesn't fly well, take it apart or build another one to make it fly better. Engineering is all about failure and overcoming that failure.

 When I do this project, I have two challenges:

1. Farthest distance
2. Trickiest rocket - boomerang and tight spiral (what I'm looking for is an indication that there was some thought behind the design)

Sometimes I change things around by asking the kids for accuracy, but they kids are pretty challenged year after year by just first two challenges.

Here are some pictures from recent classes:

From a 3rd grade class

1st 5th grade class - Distance Rocket Winners

1st 5th grade class - Spiral Trick Rocket Winners

1st 5th grade class - Boomerang Trick Rocket Winners 

2nd 5th grade class - Distance Rocket Winners

2nd 5th grade class - Trick Rocket Winners

I was stunned by the creativity of the students, but these two designs were AMAZING!

Even with the airfoil, I thought this would be too heavy with all the index card paper, but it flew beautifully.  Every time. Won the design award.

This design had a beautiful, really tight spiral, but after the tape came off, we couldn't duplicate the trick flight. But I did see it, and I couldn't deny her the design award.

Some other awesomely crazy designs are:

I tell the kids that I want them to push the envelope. Don't play safe. Think outside the box. Failure is good (one of the project's motto is Fail Spectacularly!), and I was extremely happy with this group of kids. I have more classes coming up this week, but I think it'll be hard to beat these designs. 

I might update if there's a mind-blowing one.

Enjoy and build with your kids.

NOTE: The project idea came from The Tech Museum's website a few years ago.

Awesome Books - The Naming Jar by Yangsook Choi

One of the teachers I work with at my daughter's elementary school introduced me to this book, and I absolutely loved it. Let me tell you why.
 

My family and I immigrated to the US when I was ten-years-old from South Korea. Though, at the time, I found consolation in my false impressions that my father spoke English, but I soon found out how little English he actually spoke at the time. Due to lack of English language skills, my brothers and I were teased quite often, but more than anything, our weird names painted big, fat target on our backs.

My Korean name is Ryoung Ah. This is enunciated with the silent R, usually, but the correct enunciation rolls the R in front of the y. But how could the kids in my 4th grade have known? They had to make do with a jumble of letters that you just don't see in American names very often. So, my name got butchered from Rye-young-gah to R-youn-gah, to any number of unwieldy sounds. But I didn't have the courage to correct any of them. One of my brother's name is Dong Hwan, but it got changed to Ding Dong. Dong Dong, etc. The other brother's name is Kyung Tai, but it got changed to Kee-young-tie, etc.

Needless to say, changing Korean names to American names sounded like a good idea, and we did. But even in this, my path to finding an American name of my own wasn't smooth. I liked Christine. Christine Kim had a nice ring to it. So, the next day, I went to school and told another Korean girl that beginning next Monday, I was going to everyone to call me Christine. Well, that "friend" had told everyone to call her Christine after the first recess, and I was left out in the cold. I had to start my search for an American name all over again. Finally, by the end of next week, I settled on Jennifer. I don't even remember if I particularly liked the name, but I chose it because I knew no one else named Jennifer.

With all these stories behind how I ended up with my name, I enjoyed this wonderful book and loved the choice she made. I think it was the right choice for her, but I also realize that I made the right choice for me.

I am Jennifer Ryoung Ah Kim.

P.S. I thought I should add this funny story. When we first got here, my brothers and I were desperate to make friends, and wondered why it was so hard to make friends.... Well, before we started school, my Korean-American uncle taught us a phrase that supposed to keep us out of trouble.

The phrase was... I can't speak English. Please, leave me alone.

What?!? I know.

Even now, I have a hard time believing that my uncle actually taught us the phrase thinking it would solve all kinds of problems. And here we were, wondering why we couldn't make any friends.

Awesome Books - Ender's Game by Orson Scott Card

This book surprised me in a couple of ways.

I'm pretty good at guessing the ending of the book. Maybe it's because I'm a writer, but I can consistently guess the ending. However, I had no idea how this book would end, and even a few tendrils of ideas I had, nothing worked out the way I thought it might.

The book rating on the back cover said Ages 10 and Up, but I'm not sure I agree with that. There is a certain viciousness in this book that startled and shocked me. I didn't expect it from such a young character. Although a lot of books have Ages so and up, usually the kids who are at least 2 or 3 years younger start to read up to the age rating. At that point, I feel that this book is not appropriate for kids who are younger than 10. AND I wouldn't let my daughter read it until she's about 11 or 12.

HOWEVER, I enjoyed this book, and I'd like to recommend it to anyone who likes a good action/adventure. That is anyone older than 10, but probably 12.

Spoiler Alert~

Ender lives in a dangerous world where the Aliens nicknamed "buggers" have invaded the earth twice already. Every Earthlings' life is predicated by the impending third bugger invasion.

In this world of limited resources and impending doom, Ender is also a dreaded "third." In a world where there is two-child-per-family policy, being a "third" itself is a reason for derision. He is picked on by his classmates, and he is harassed by his older brother who resents him for being more talented and capable of meeting the demands of military training.

But he is a cunning, ruthless, military genius, and he is sent to Battle School to hone his strategic and tactical skills pitted against other brilliant students of Battle School. There, he excels once again by coming up with mock battle plans that surprise and impress his superiors. His team never loses a battle, no matter how it is outnumbered and disadvantaged. His successes in Battle School convince his teachers to Command School, skipping several years of additional training.

In Command School, he is isolated from the rest and interacts mostly with his mentor, the previous conflict's war hero, Mazer. He spends most of his time fighting buggers in simulation, and he is depressed by the endless simulations and isolated existence.

For his "final" test, Ender's fleet is outnumbered by the buggers by a lot, and he sacrifices most of his fighters to launch a weapon that destroyed the entire bugger planet. Ender thinks this act of rebellion will get him kicked out of Command School. Instead, he learns that the "simulations" weren't simulations. In fact, they represented the actual international fleet, buggers' fleet, and buggers' home world. Ender has won the bugger war for the humanity.

Winning the bugger war has opened a bigger can of worms on Earth where various powers fight amongst themselves for the control. Due to his capabilities, he cannot return to Earth. He decides to become a colonist on one of the buggers' worlds. There he learns that bugger invasions were based on misunderstandings and mistakes, and he finds a dormant egg of the bugger queen. In the end, he and his sister board a starship to search for a safe world to establish another bugger colony.

I skipped a big chunk of plot that involves his brother and sister, but I wanted to concentrate on Ender. I really enjoyed the strategy and tactics Ender used to win his mock battles in Battle School and Command School; however, I had problems with what finally led to Ender's entry into Battle School and Command School. His brutal beating of a classmate bully lands him not in jail, but in coveted Battle School. And when he is ambushed, he responds with overwhelming force, and it gets him promoted to Command School. In both cases, his opponents are dead. It's this rewarding of his ruthlessness that I find objectionable.

However, I did enjoy the book. In fact, I'll probably read it again. It made me think about a lot of things, from space colonization to alien life forms to morality of preemptive strike, communication obstacles between two vastly different species, etc. Though I did have some reservations, I would recommend the book to those who enjoy action or sci-fi.  

PS - I also read Ender's Shadow, and the same brutality, cunning, and ruthlessness are threaded in this book for a main character who is even younger (starts out at 4), and I just couldn't recommend the book. And I didn't enjoy it. It was too much, but I finished, hoping that things would change. It didn't.