At the start of Term 4, 3WJ began learning about the genre of explaining. We have identified cause and effect relationships and how to order an explanation so that it makes sense. We originally practiced explaining our unique inventions that we drew diagrams of and wrote a full explanation for.
This week, we have been looking at scientific explanations. We have carried out a few small science experiences in class that we have written about. On Monday, we observed raisins in soda water (dancing raisins), the effects of soft drink on copper pennies, and the physical evidence of how a paper towel works.
Dancing Raisins – by Otto
When you do this experiment, you will find the raisins will drop to the bottom. This is a result of their density, but because raisins are rough and dented, they are full of air pockets. Next the air pockets attract CO2 gas in the liquid, creating the little bubbles you see on their surface. These bubbles increase the volume of the raisin, but contribute little to its mass. Because the raisin has higher volume, it displaces more fluid, applying force that pushes the raisin up. When the raisin hits the surface, some of the bubbles pop, and the raisin sinks again. The process is repeated, making it look like the raisins are dancing.
Dancing Raisins – by Jaimie
As we observed the ‘dancing’ raisins, we noticed the sultanas sink to the bottom. This is caused by the mass of the raisins pulling down on the carbon dioxide gas. It is similar to if you get a prep to hold a grade twelve, the prep is too light, and the grade twelve is too heavy. As a consequence, the prep falls down.
This is occurring simultaneously to the other raisins being pumped
with air pockets and lofting up to the surface then coming back down.
We see these bubbles are increasing the volume of the raisins,
but they still contribute very little to it’s mass because it’s the oxygen
that’s making it expand.
In the end, we see this wonderful experiment as dancing raisins. So now you can do this yourself and know how it works! Thank you for reading!
Cleaning Pennies – by Isaac
Firstly if you put dirty pennies in some cola, it will dissolve the dirt on the pennies. But finally to tell you how the dirt got there. So the pennies are made out of copper. Copper has a reaction to air
that makes copper oxide (the dirt we see on the pennies) which is reacted on when the pennies are in soda.
Cleaning Pennies – by Olivia
Do you wonder if the pennies in soda trick actually works? Here’s your answer. You need to know how the pennies get dull in the first place. Well all pennies have copper in them. When the copper meets the air, it reacts. It causes copper oxide to form on the pennies which makes them look dull.
After that, you would want to know if pennies actually get shinier if you put them in soda, and incredibly they do! Here’s why: soda has an acid in it called phosphoric acid. Phosphoric acid dissolves copper oxide. So finally when you put the pennies [ covered in copper oxide ] in the soda, the phosphoric acid dissolves the dulling copper oxide so the pennies look shinier.
Paper Towel Art – by Jayden
When you put the ice cube on the paper towel, it starts to melt.The paper towel is getting soaked. That’s because the water is being absorbed. The spread of liquids happens through small gaps in the paper towel. Then the paper towel is spreading water that likes to stick together, like when you pull someone up and then they pull you up. The ice had to melt to make the colour spread everywhere. I put purple, but as the water spread it had pink and blue.
Paper Towel Art – by Orla
First the ice cube will slowly melt and turn into water. After that, the water will be absorbed gradually into the paper towel, and it will very slowly spread across the paper towel. It will then soak though, and then it makes a pattern and swirls of colour by picking up the dye from the texta and mixing it with other colours.
Paper Towel Art – by Mardi
When the ice cube melts, the paper towel absorbs it. Next the paper towel has holes that let gases and liquids through. Finally in the end, water likes to stick together, like pulling each other up a ladder, and that’s what happens. The water sticks to the paper towel, and as the water comes in, it pulls its buddy along. This causes the water to go further up the paper towel which is why the colours all mix together.