We started this lab by making an NGSS outline for a baking soda and vinegar experiment.
Our question we are posing to frame student investigations is: Does the weight of vinegar and baking soda change when they are mixed together?
Asking students to keep this in mind, we would ask students what they think will happen when we mix these two substances. Would it still weight the same? If it changed to a gas or solid, would it weigh any different? Write down a prediction on what you think is going to happen during this experiment.
Weight of the substances before reaction: 57g
Vinegar: 41.5g Bag weight: 5.1g
Baking soda: 10.4g
Weight of the substances after reaction: 55.2g
Weight of liquid when poured back in beaker: 46.8g
Limitations: not all of the gas being gathered between pouring in baking soda and closing the bag, not all of the liquid came out of the bag when poured back into the beaker.
Students can compare original weight to final weight, take into consideration the limitations. The weight of the substances put into the bag before the reaction was 54.9g, but the weight of the liquid after the reaction is 46.8g. The amount went down, but the total weight was still almost the same. Ask students where the matter went, and how did it still weigh almost the same. Students can hypothesize that the matter turned into gas when it bubbled and fizzed. Explain that the substances interacting created a gas that we can only see when its inside the bag.
After this, we discussed some ideas of how to create a lab on vinegar and baking soda. I used ideas that I had done in the past with these substances, but we also learned some more ways to explore the conservation of matter when mixing these. Collaborating with other groups was useful because we all went about this in different ways. I learned that it is important to create open-ended labs that allow more conversations about other properties other than the ones the lab specifically focuses on.
I also liked being able to talk with other groups about what methods they used for their experiments. It gave me some good ideas and helped us solidify evidence for our own experiments. It also reinforced the idea that you wrote about, that students should be given open-ended labs so they can be creative and use discussion to deepen understanding.
ReplyDeleteI think it was great to share our findings with each others groups to learn from our mistakes and other successes. It was a great way to facilitate critical thinking skills.
ReplyDeleteIt is always a smart idea to have your students collaborate with each other to explain their thoughts and findings. It helps them to learn other perspectives and maybe learn something new.
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