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Masterchemistry Understanding Chemical Reactions
Predict
"That food colouring was added to water, changing the colour of the water"
"In the test tubes there was different universal indicators that reacted differently to acids and bases in the beakers, using the pH scale"
Now I Know
Change in Thinking
"I thought that the test was simply just water and food colouring, but now I realise that it was an experiment using the pH scales, comparing acids and base"
The activity was based on the format of Masterchef. Students were grouped into teams by performing a chemical reaction. Conical flasks with various clear solutions were placed in a row on the table. Each student poured a test tube which contained universal indicator and observed the colour; blue, red, green, yellow. Once grouped, students had a series of reactions/recipes to perform at their own stations.
The Year 10 Chemistry Unit is taught through the investigation of Food Chemistry. The particular focus of this stage of the unit is understanding chemical reactions through Food Chemistry. The students had no formal prior knowledge of the types of reactions that would occur in the experiments. The focus of the experiments was to explore the chemical reactions through an inquiry based model. Chemical reactions would be demonstrated with common everyday household ingredients.
The students were engaged and worked collaboratively in groups. The structure allowed the students to see the learning and understanding process, and afforded them with the opportunity to reflect on their understanding of chemical reactions through the medium of food chemistry experiments. The ability as a teacher to allow the students to form their own understandings was far more powerful than providing them with a theory lesson on chemical reactions.
The process of this experiment allowed the students to explore their prior knowledge, determine its accuracy, and then explore and extend their understanding of chemical reactions. Many of the students, through their reflections, noted that their understanding of chemical reactions had changed. Students had to think carefully about why a reaction occurred, or did not occur, conditions required for the reaction to occur, and support their conclusion.
%22When%20making%20sherbet%2C%20I%20didn%u2019t%20realise%20it%20was%20a%20chemical%20reaction.%20I%20thought%20that%20the%20fizzy%20taste%20from%20sherbet%20was%20just%20the%20citric%20acid.%20But%20now%20I%20know%20that%20the%20fizzy%20taste%20in%20my%20mouth%20comes%20from%20a%20reaction%20between%20the%20citric%20acid%20and%20the%20bicarbonate%20soda.%20Producing%20carbon%20dioxide.%20So%20in%20fact%20there%20was%20a%20chemical%20reaction%20when%20making%20sherbet.%22
"I thought the honeycomb mixture would harden and create solid particles, but now I know that it actually becomes like a soft caramel sweet and was liquid-like."
%22I%20initially%20didn%u2019t%20realise%20that%20there%20was%20a%20chemical%20reaction%20to%20making%20honeycomb.%20I%20thought%20that%20the%20toffee%20mixture%20boiled%20due%20to%20the%20heat%20and%20froth%2C%20not%20because%20of%20the%20reactants.%20But%20now%20I%20know%20that%20when%20the%20bicarbonate%20soda%20reacts%20with%20the%20sugar%20mixture%2C%20bubbles%20occur%20from%20gas%3A%20carbon%20dioxide.%22
Students recorded their prediction for each reaction. By making accurate and thorough observations, students were able to reflect on the nature of the chemical reaction and therefor analyse how their thinking has changed.
"When I saw that all the ingredients were solids I was convinced that the water would not be produced, however when I tasted the sherbet it was evident that the carbon dioxide was present in the bubbles."