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. 

These are the gifts I pick for other kid's birthday party?

Experiment #4 : How solid substances can rise water level ?

During bed time, I read a story in English and Tamil to Katli. I narrate stories like thirsty crow, greedy fox in Tamil. Those were the stories I grew up listening to. On one particular night, he asked me how water comes up when thirsty crow throws stone into it. I said since stones are heavy and they settle at the bottom. He remembered the previous experiment we did on light and heavy object and said that's because they are heavy. I was so thrilled that he recollected it. 

I continued saying that water flows in-between the stones like how you squeeze through your caterpillar tunnel tent. He smiled. He asked whether we can try doing it at home. I was excited that he came up with the idea for our next experiment. So here we are testing with items from kitchen. 

Aim: 

To check how much water rises with three different sized items

Things needed:

• Three cups and three glasses
• Dry pinto beans, handful
• Dry mung bean, handful
• Dry mung dhal, handful
• Water as needed

Method:

1. Place the bowl and glass against each other as shown in the picture.
2. Fill the glasses with little water, make sure that they are all on the same level
3. Place the beans and lentils in the bowl
4. Ask the child to fill each glass. You can ask the child to count the beans / lentils as they add them. My son could count up to 30. You can go with whatever number the child knows. 
5. They will be excited to see the water come up. You can tell the thirsty crow story and explain it.
6. I left the beans and lentils in water overnight.
7. Next day, we made an easy microwave snack with moong dhal (Haldiram style - recipe here). You can ask the child to help as it involves no cooking. My son helped with this.
8. I plan to show the concept of germination with soaked moong dhal, that's what we do during Navaratri (Indian festival) - more details in the next post)
9. Lastly with the soaked pinto beans (recipe here), I made a simple curry for roti. 

Beans /Lentils are overnight soaking. My son said that they drank the water and became big

Tips to improvise the project:

1. They can learn counting through this experiment
2. Mix the bowls and glasses and ask the child to place it against respective colors
3. Teach them about sizes - small, medium and large
4. Remind them about our experiment on light and heavy object and keep reminding them that these solids settle at the bottom as they are heavy. Sometimes the skin might come of the bean and float, that's gives us a nice opportunity to say that light objects float. For kids to remember concepts, these things need to be said repetitively.

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 #2: Identifying the difference between floating and sinking objects

Today we are back with second experiment for the kids. 

Kids generally love to play with water. My son enjoys dipping his fingers or splashing it around or clapping inside the water. I wanted to use that interest of my son. We did this experiment for three times. So for the first time we ran the experiment with objects from his toy box, for the second time it was kitchen ingredients like lentils, garlic peel and for the third time, it was leaves, flower petals, stones and twigs. Now he knows that if it's a rock, its heavy and it will sink while garlic or onion peel will float as it is light.

This experiment will form a base for their future grades where they will try to analyze the difference between the objects by concepts of mass, volume, weight and surface area measurements. Do try this fun activity with your kids to build their thinking abilities.

Aim: 

To identify whether a list of objects sink or float in water

Things needed:

1. Objects from kitchen, toy shelf and outside like parks (lentils, rice, garlic, its peel, onions & its peel, straw, leaves, flower, tiny toys)
2. A clean plastic tub
3. Water to fill it
4. Lots of enthusiasm and encouragement from parents 

Method:

1. Assemble the tub with water in a place convenient for kids to spill and mess around
2. Gather the objects in a basket. You can ask the kid to identify the object and tell its color as well.
3. Start by asking the child to guess like what do you think will happen if we drop this object. Let the kid do it and see what happens.
4. When it sinks, explain to him that it sinks because it is heavy.
5. When it floats, explain to him that it floats because it is light
6. Ask him to remember and count the number of objects that float and those that sinks.
7. Repeat the experiment few more times for him to understand the concept well.

Result:

They will love to see difference between floating and sinking objects. They will interact and talk when you ask them questions like what is the color of this object, what is the size of it. It will be a time well spent with the child. You can play around with different objects. My son asked whether he could drop the phone and see what happens. So be prepared for interesting questions.

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.