Assessment task 1 working scientifically


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Assessment task 1 working scientifically

  1. 1. Part A: Working ScientificallyInvestigation 1 – How well does dishwashing liquid repel against fat?IntroductionPrior to completing the activity I wrote down what I think would happen when I addeddishwashing liquid to various types of milk, these being full cream, smarter white andskim milk.We placed 1 drop of red food colouring on one side of the bowl and a drop of bluefood colouring on the other side of the bowl directly opposite the red colouring. Bothdrops were about 5cm in from the edge of the bowl.PredictMy prediction is that once the dishwashing liquid was added to the bowl thatcontained the full cream milk, the colours would dissolve and disappear. I predictedthat this would happen to all 3 types of milk, however I believe that the colour wouldnot fade as much in the skim milk as they did in the full cream milk. I believe thatthis would occur due to the dishwashing liquid reacting to the food colouring in themilk.Wendy Johnstone Science Curriculum and Pedagogy 1
  2. 2. ObserveWhen we placed the drops of food colouring in the bowl we saw that it did not moveit just stayed as a drop in the bowl of milk. We then added the dishwashing liquid inbetween the food colouring and as soon as we did this the food colouring reacted bymoving away from each other to the outer rim of the bowl.The food colouring sank into the milk for the first part and there was a small thinoutline of the food colouring around the edge of the bowl that went for about 5cm.We watch the bowl and we could see that nothing was happening as we continued towatch the bowl we noticed that the colours were starting to move and react to thedishwashing liquid.As a group we asked ourselves “what was moving”? “What was happening”? Wenoticed that the colours were swirling in the milk and we believed that there was areaction with the detergent and the milk. Some of the suggestions that we came upwith as to what was happening was that perhaps the milk was separating or wascurdling. We did notice that the two colours separated from each other, moving toopposite sides of the bowl. We also considered whether the reaction was due to thefood colouring being in the milk or would it still have the same reaction if the foodcolouring was not in the milk.We completed the investigation again however this time we used the “smarter milkwhich had 2% fat. We again put the drops of food colouring in the bowl followed bythe dishwashing liquid in the middle of the food colouring. This time the reaction wasWendy Johnstone Science Curriculum and Pedagogy 2
  3. 3. the same in the fact that the food colouring sank, and then began to swirl aroundhowever the reaction was a lot slower and did not go for as long as what it did withthe full cream milk.The third investigation was to complete it again, however this time we used skimmilk. When we put the dishwashing liquid into the milk and this time the coloursactually swirled together, but did not mix. The blue colouring sat on top of the redcolouring but they did not mix together.ExplainWe know that the reaction that we were seeing was in the dishwashing liquidrepelling against the fatty milk. It was not the food colouring that was repellingagainst the milk or detergent and the colouring was there to help show how the milkwas reacting to the dishwashing liquid.Steve Spangler explains that the reason it reacts like this is “due to the detergentsbipolar characteristics (nonpolar on one end and polar on the other), weakens thechemical bonds that hold the proteins and fats in solution. The soaps polar, orhydrophilic (water-loving), end dissolves in water, and its hydrophobic (water-fearing)end attaches to a fat globule in the milk”.He continues on to explain that “The molecules of fat bend, roll, twist, and contort inall directions as the soap molecules race around to join up with the fat molecules.During all of this fat molecule gymnastics, the food coloring molecules are bumpedWendy Johnstone Science Curriculum and Pedagogy 3
  4. 4. and shoved everywhere, providing an easy way to observe all the invisible activity.As the soap becomes evenly mixed with the milk, the action slows down andeventually stops.We can see from the evidence of the photo below the milk reacting to the detergent.So we can look back at our question for completing this investigation – How welldoes dishwashing liquid repel against fat? I think that we can clearly establish that itactually repels more intensely as the milk with the higher fat content had a moresignificant reaction than the milk with the lower fat content.Wendy Johnstone Science Curriculum and Pedagogy 4
  5. 5. Part B: Australian Curriculum – ScienceScenario 2 – Year 3/4StrandSub- strandAims Learning Design (around scenarios)An interest in science as a means of expanding their curiosity andwillingness to explore, ask questions about and speculate on thechanging world in which they live.An understanding of the vision that science provides of the nature ofliving things, of the Earth and its place in the cosmos, and of thephysical and chemical processes that explain the behaviour of allmaterial thingsAn understanding of the nature of scientific inquiry and the ability touse a range of scientific inquiry methods, including questioning;Wendy Johnstone Science Curriculum and Pedagogy 5
  6. 6. planning and conducting experiments and investigations based onethical principles; collecting and analysing data; evaluating results; anddrawing critical, evidence-based conclusionsAn understanding of historical and cultural contributions to science aswell as contemporary science issues and activities and anunderstanding of the diversity of careers related to scienceA solid foundation of knowledge of the biological, chemical. Physical,Earth and space sciences including being able to select and integratethe scientific knowledge and methods needed to explain and predictphenomena, to apply that understanding to new situations and events,and to appreciate the dynamic nature of science knowledge.Wendy Johnstone Science Curriculum and Pedagogy 6
  7. 7. Referencingwww.stevespanglerscience.comWendy Johnstone Science Curriculum and Pedagogy 7