Physical science

silk

sound: Prepare in advance a cutting board and several pieces of silk fabric. Say: let's listen to what sound the silk fabric will make. Remember that soundwaves are created when some energy is applied to the object. Then molecules of the medium start moving pushing other molecules, making them vibrate. That’s how the sound is created. Let's listen to the sound that the silk fabric will create. Take a piece of the silk in your right hand and let it drop on the cutting board. Say: can you hear the sound? It seems that silk is so light, that almost no sound is produced by it! Let's do it again! Put the piece of silk fabric in the baby's right hand and let the baby try to squeeze, crinkle and fold it. Say: can you hear any sound?

elastisity and plasticity: we know that elasticity is ability of the object to retain its size and shape after removing the force that is applied. If the object does not deform, it is considered very elastic. Let us see if silk fabric is elastic. We will make an experiment. We will bend the piece of it and see if it will deform. What do you think will happen to silk fabric? I think it will bend. Now let's conduct an experiment. Take a piece of silk and bend it in your right hand. Place another piece of silk in the baby's right hand and let the baby bend it. Help if needed. Observe silk fabric. Say: I see that silk deformed, it remains bent. Hence we can conclude that this material is not elastic. Remember, that plasticity can be tested in the same way. If after bending the object retains the new form without rupturing or breaking, it means it is very plastic. Our silk is plastic, because it remains bent.

Hardness. Say: I wonder if silk fabric is hard. When we say the object is hard, we mean next: when I scratch it with another sharp object there is no sign left on it. It is very difficult to leave traces on it. If the object is hard it means it is resistant to permanent shape changes. Do you think the silk fabric is hard? Let's make a hypothesis. I think it is not hard. Let us conduct an experiment in order to prove or disprove our hypothesis. We will need a coin for that. Place a piece of the silk fabric on the cutting board holding it by your left hand and take the coin in your right hand. Make sure your hands are in front of the baby's face so he can see well what is happening. Say: let's scratch the object with the coin. Do that. Say: let's observe now. What do you see? Do you see any holes left on the surface of the silk fabric? Did the surface get deformed? Yes. It did. It means the silk fabric is a soft object, not hard.

Let’s explore if silk fabric is waterproof and absorbent. A material is waterproof when it repels liquids. What do you think about the silk fabric? Is it waterproof? I think it is not. Now let's make an experiment to prove our hypothesis. Take a large pot. Put a jar/cup into it. Put a silk fabric on top of the jar/cup so it will cover the opening like a lead. Say: let’s observe. Poor water on the silk. Say: the silk is not waterproof; water can go through the silk into the jar/cup. What is absorbancy then? It is ability of any material to soak up the water, right? What do you see happened to the silk? See it soaked up some water. Let’s squeeze the silk now to see how much water got into it. Squeeze it. Say: see, there is little water coming out of it. The silk has low level of absorbency.

Glossy/mat: Say: The (object) is shiny/glossy/mat. (glossy - reflects the light, mat - absorbs the light)

Brittleness: DO you think the (object) is fragile? Make an assumption. The characteristic for fragility is brittleness. We will drop the(object) from up to the ground and observe if it breaks. Let’s do an experiment. (Take an (object) and drop it from stretched high hand). Say: look at the (object), it did not break at all! It is not brittle. Or it broke and it is brittle.

Magnetic: Let’s see if it is magnetic. We will get a magnet and put it close to the (object). See: the (object) is on the same place. It does not move so it is not magnetic.

Transparent, translucent, opaque: Hold the (object) in your left hand in front of the baby and say: (baby's name),do you think (object) is see-through? Le's make a hypothesis. I thinks it is. Now we have to make an experiment to prove or disprove it. We will need a dark room and a flashlight. Make the room darker or go to the dark room. Place the object in the left hand and the flashlight in the right hand. Switch the flashlight on and say: let's observe if the light goes through the (object). Say: I can see some light passing through the leaf. It is translucent. (If your leaf is thick – you cant and then the leaf is opaque).

Fluid.Now we will see if the (object) is fluid. My hypothesis is that it is not. We will conduct an experiment in order to check it out. Hold the (object) in your right hand with two fingers if possible. Say: Look! I am holding it and it does not change its shape and does not move at all. It does not flow.

Soluble: Let’s see if it is soluble. What do you think, is it soluble? I guess it is not. Let's again make an experiment and check it out. We will need some water. Take an empty bowl, pour some water into it. Put the leaf into water again. Say: look the leaf does not dissolve in the water. It remains as it is. It means it is not soluble.

Insulator: If we put a lot of leaves together in a pile, they will be a good insulator. They will keep warmth inside.

Burn: (object) contains oxygen molecules and can burn with high temperatures. (explain about your object)

Let’s check if the silk piece is made of a ductile material. Let us try to stretch it and observe if it becomes a wire.If it does, then it is ductile. Start stretching. Say: see, the silk is very hard to stretch! It is not stretchable at all. Hence It is not ductile.

Our (object) smells so fresh and nice! Or describe how it smells

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