Experiment #8: Soap Bubbles

Soap bubbles are interesting for everyone. My 18 months old girl loves it, my 4.5 years old boy loves and I love it too. Yesterday my mother-in-law was busy cooking an awesome Tamil Nadu meal of Mutton Biryani, Mutton Curry, and Rasam. On Saturday we went to Hidden Villa, Los Altos. I have shared details in this post.

Since I had the time, I decided to spent it with my kids. We were snacking on pistachios and saved its shells to make art work. We will reveal it next week as he needs to paint the dried shell. We made a greeting card with it.

 

After that we did an experiment with soap bubbles. Water excites my son. He loves to play with it all the time. Yesterday we used water, soap and straw to make bubble mountains. When air is blown through straw into a container, cascades of bubbles are created which rises high and falls over the rim.

 

 

 

What is the science behind bubble?
In our case, I had the opportunity to talk about shapes and light. For older kids, we can talk about surface tension, geometry and chemistry. For pre-schoolers like my son, this experiment will help them investigate, discover and explore the world of magical bubbles.

 

What is a bubble?

 

A bubble is nothing but air wrapped in soap film. It is made of soap molecules. The bubbles always take a sphere shape because that has the smallest surface area for the amount of volume. When you blow, bubbles stretch and takes all crazy shape. Once its sealed and release into the air, the tension in the bubble skin shrinks to the smaller shape for the volume of air that got trapped inside it.

 

What you need?

• 8oz plastic tumbler
• Few drops of dishwashing soap
• Straw
• Happy kid who loves bubbles
• Kitchen Sink or Bathtub or Patio or Backyard

How to do it?

1. Add water to fill half of the tumbler. Add few drops of dishwashing liquid. Stir with the straw.
2. Ask the child to blow air through the starw so bubbles start emerging on the surface. Let the child to make a tall mountain.
3. Repeat and let the child have fun

As he made the bubbles, I asked him the following questions.

1. What is the shape of the bubbles?
2. What colors do you see?
3. How high can he make the bubble fountain?

 

My 18 month old daughter stood next to him and kept popping the bubbles. She enjoyed it too.

 

 

 

Have you noticed that bubbles pop even without being touched or poked?

That is because they pop when the water between the soap film surface evaporates.

 

We did the experiment in the kitchen sink. There is a window right above the sink. The sun rays fell on the bubble and gave a prism effect. Katli was excited to see rainbow colors in the bubbles. A buble gets it color from light waves reflecting between the soap film. Bubbles can also reflect whats around them like the faces around them.

 

In the picture, you can see that the bubbles got the hexagon shape. It looked like beehive. When bubbles are about the same size, they form perfect hexagons. My son has always seen only bubbles that are round and so this was something new for him.

 

 

Experiment #6: Does clementine/ orange float or sink in water?

Katli and I are back with another experiment after a short hiatus. I started work in February after the maternity time off. It took us sometime to adjust to a schedule and finally we are here to share an experiment with our favourite ingredient - WATER. Yes my son loves to play with water.

Yesterday we were at my friend's place to celebrate Holi (Indian festival that is celebrated with colors to welcome Spring). The kids enjoyed the most as we let them play with water. On the drive back home, I asked my son the name of the festival he celebrated. His reply was "Splish Splash Festival". He didn't remember the word - Holi but all he recollected from yesterday's party was having fun with water.

Coming to our experiment, let me tell you what we have for you today. We enjoyed eating a lot of clementines/oranges since February. So I planned an experiment with clemetines, green grapes and potatoes.

Aim

To see whether clemetines, grapes and potatoes float or sink in water

Things Needed

• Couple of clementines or orange
• Few green grapes
• Couple of potatoes
• A deep container / bowl filled with water

Directions

1. Prepare the working area. Make sure it can stand all the water spills. I do the experiments in kitchen island. Fill the bowl with water.
2. Put the orange in the water and watch what happens.
3. Put the grapes in the water and watch what happens.
4. Put the potatoes in the water and watch what happens.
5. Peel the rind from the orange and try the experiment again, ask the kid what he/she sees.

What actually happens?

When you put the orange in the bowl of water it floated on the surface. But after you removed the rind,it sinks to the bottom. But that was not the case with green grapes or apple, they sink to the bottom all the time.

The rind of an orange is made of tiny air pockets . When placed in water, they float as the air pockets give it a lower density than water. So when rind is removed, all the air pockets are gone. The orange now sinks as its density is higher than that of water.

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Experiment #5: Why does water from an inverted glass not fall when it is covered with a piece of cardboard?

We are back with another famous experiment I have done in school. It was in my physics lab. I went to a Central Board School and I am proud to say that science experiments which were part of my syllabus has made me love science more than any other subject.

As a part of our syllabus, we attend Prayoga (a non profit school science education project by Stree Seva Mandir) in Grade 8. Prayoga continues to motivate the students to enjoy science experiments and I am really thrilled that my school was part of it.

Now coming to our experiment, we used tea coaster as a cardboard base and one of Katli's tumbler to fill water. 

Aim:

To see why water from an inverted glass doesn't not spill when it is covered with a piece of cardboard?

Things Needed:

• 1 plastic cup
• 1 piece of cardboard ( little larger than the size of tumbler's mouth)
• Water to fill it half
• A parent to help

Directions

1. Prepare the working area.Make sure it can stand all the water spills. I do the experiments in kitchen island.
2. Place a large tray below and place cup inside. Fill it with water. Hold the cup in one hand.
3. Place the cardboard on top of the cup. Make sure one of the parent is performing the experiment with the child. Hold the cardboard with your left palm assuming your holding the cup in right hand.
4. Turn it upside down, then back and again invert it.
5. Now slowly remove your left hand and hold the cup firmly. The cardboard will stay intact and will not fall down. Tell the child that its a magic. And repeat it so many times as children see the experiment like a magic show.

What actually happens?

When the cup is inverted with a tightly fit cardboard at its mouth, the water doesn't leak.  The cardboard along with the surface tension of water forms a tight seal at the mouth of the cup. Remember even if a single drop drips out of the tumbler, the cardboard will not stay. The absence of atmospheric pressure creates a vacuum. The cardboard stays intact as atmospheric pressure outside is greater than the one created inside the cup. That pressure holds the cardboard and prevents water to leak. 

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Experiment #3: How to create tornado in a bottle?

What is a tornado?

Wikipedia defines tornado as "A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones,although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation."

My son and I decided to create a tornado in a bottle. We can replicate the effect on a smaller scale with simple items like dish washing liquid, glitters, water and bottle. 

Aim: To create tornado in a bottle using simple kitchen items

Things needed:

1. 1 glass bottle
2. Water to fill it 3/4 th or less
3. Glitters ( I bought this at Walmart)
4. Dish washing liquid 
5. Funnel

Method:

1. Set up the working area. I used a plastic tray to catch the spills.
2. Fill the bottle with water (3/4th or less)
3. Add few drops of dish washing liquid
4. Place the funnel in the neck of the bottle, ask the kid to sprinkle lots of glitter into it (More glitter in the water, more visible will be our tornado in a bottle)
5. Tightly screw the cap to the bottle. Check well so there is no leaks
6. Turn the bottle upside down and hold it by the neck. Spin the bottle in circular motion for some time, about 10-20 seconds, stop and look at the mini tornado forming in the water. 
7. We had to try it few more times to get it right. So keep swirling it and sing to your child for each round you make:

"Round and round the garden

Like a teddy bear

One step, two step

Tickle under there"

What actually happens?

When you spin the bottle in circular motion, it creates a water vortex. You will see water spinning around the center of the bottle. This is due to centripetal force. It is an inward force which directs the object (in this case water) towards the center of its circular path.  This effect looks like a mini tornado.

Experiment #1: Inflate a balloon with baking soda and vinegar

My mother played a key role in molding my thought process. She would talk science behind simple concepts like what happens when yeast is added to idly batter, process of fermentation, how curd is formed, prism effect, chlorophyll experiments on a day-to-day basis. Like its part of her conversation. We would do projects like drip irrigation or windmill generation model plants for Navaratri, a South Indian festival. I owe my interest in science to her. Since the whole concept makes you think and get creative, I am trying to inculcate the same interest to my son.

Today  I am sharing details about a simple experiment which we did with Katli during last three weekends. I feel doing certain things repetitively makes the kids remember it better. After all practice makes a man perfect right?

I am going to follow the template I have used in my school days.

Aim: To see whether the balloon gets inflated using baking soda and vinegar

Things needed: 

1. 1 small empty glass or plastic bottle (We used 500 ml lemonade bottle)
2. 3-4 tablespoon baking soda
3. 1/2 cup vinegar
4. 1/4 cup water (use in method 2)
5. Funnel
6. Small Balloon

Directions: We followed two methods to compare which method was better.

Method 1 (no water involved):

1. Stretch the balloon well. Gently tap the baking soda into it. Set aside.
2. Add the vinegar to bottle. Place the neck of the balloon over the bottle opening. Don't let the baking soda fall into the vinegar.
3. Once everything is set, gently lift the balloon.When the baking soda falls or comes in contact with vinegar, fizz is produced. This will cause the balloon to inflate.

Method 2:

1. Start by stretching the balloon well. Set it aside.
2. Carefully pour the baking soda into the bottle using the funnel (refer the pictures). 
3. Add water and dissolve it. 
4. Pour the vinegar and wrap the neck of the balloon into the mouth of the bottle. Watch the balloon inflate. This method made the balloon inflate to a small size. This was because when vinegar was poured, the reaction started to happen well before the balloon was attached to the bottle neck. Some gas was lost to the surrounding hence it wasn't as effective.

What actually happens?

It is a simple acid-base reaction. When baking soda and vinegar comes in contact they react to produce carbon dioxide. The gas spreads out and reaches the balloon which gets inflates it. 

I explained in a much simpler way to my three year old son. I said when this white powder touches the vinegar, magic happens. I told him to watch the fizz and see how the balloon grew in size. He was excited and wanted to do it again. 

How to improvise the experiment?

1. Increase the amount of vinegar or baking soda and note the change.
2. Use balloons or bottle of different size and see how big each balloon gets.

Next post is about understanding the difference between light and heavy objects.