I am sitting in our charchaa session this morning, my favourite place to be. Charchaa is the morning space where we get together as a team and dive into a concept, mainly of Math or Science. This space is loved so much by everyone one, that our people definitely reach before the charcha time i.e. 9:15am!
Today’s Charchaa is learning about a specific property of objects – trying to understand why some things float, and why some things sink. Rather simple idea! But we will discover something new today, develop a deeper understanding, that I am sure of. In the earlier charcha we had explored what things float. We had realised that for several things our guesses were off the mark. Like tomato, eraser, lemon, water bottle – will they sink or will they float? We had guessed and then tried it to find out if we were right. I learnt something about our youngsters through this exercise – Its seems they had not washed tomato or onion or chillies that often. Have they not cooked that often?
In our discussion we had concluded that it must have something to do with the weight of the object, and the space that it occupies.
Today we are measuring their weights and the spaces they occupy. There is so much excitment in the group. They all know how to measure weight of any object, but there is a struggle around how to measure the space occupied by the onion or tomato or water bottle? Time for you the reader to think, how would you find the space occupied by an onion?
Some of them have studied volume in math recently. Can we calculate by approximating onion to be a sphere? We could measure it’s height and width, approximate it as a sphere and then calculate. Is there an easier way? Do were really need to do all that calculation? We measure water volume in liters. Can’t we some how do the same thing here? Can we just measure the volume of onions in liters? Will we have to make onion juice and then measure? Then what about the space occupied by the onion flesh? There’s got to be a better way! Wait a minute, we could push the onion inside water and measure the level of water that rises. The millilitres of water that rises up would the volume that onion occupies. Easy! We know the volume!
We as a team start to measure the weight of every object and measure it’s volume. We come up with a table of about 10 objects – their weight, the space they occupy i.e. volume, and if they sink or float – block of wood, block of iron, stone, lemon, onion, tomato, potato, closed plastic box etc.
The next challenge was to weigh the object, put it in water to find out if it sinks or floats. Now we had to guess what could be its volume based on the data of 10 objects we already had. Fun! Fun! Fun! Its time for making predictions. We were able to make the predictions. We tried estimating the volume of the woods piece, iron piece, a box of iron filings, small plastic box and so on.
We had been measuring all the weight in grams and the volume in millilitres. Someone noticed that whenever something sinks it’s mass value in gms is more than the volume value in mls. But how can you compare? One can’t compare gms with mls! Someone comes up with another smart idea. What about measuring how much amount any object weighs for a given volume. In other words, how dense the object is… Its density. Instead of comparing by subtracting, we compare by dividing i.e. not how much more difference, but how many times difference. We define denseness of an object as how many gms in given mls I.e. ratio of mass to volume. We observe from our data that when this density is more than 1 gm per ml, the object sinks, and when it’s less than 1 it floats on water.
Now imaginations are running wild – Oil floats on water. Its denseness must be less. Different liquids might have different densities. Will onion float on oil or sink?
Something floating in air must also follow something similar too!
Can we say anything about how fishes use this idea to come up to the surface or go down?
Would things be different in river versus salty sea water? Is that how people float in the so called Dead sea?
Its 10:15am. Its time to close the charchaa space. Nobody is ready to leave. We have more questions than we have found the answer for. We want to know more discuss more. But that will be tomorrow. Time to get on with the work of the day. Educate more teachers, teach more students. And hope that each one of us is able to create the same joy and excitment in our classrooms that we experienced in our morning charchaas.