Lab Week 15: The Last Week!

Today in lab, we used baking soda and vinegar to demonstrate that matter is conserved no matter how we mix substances or how they react. We used this experiment to develop a lesson plan of how we could teach this in a fifth grade classroom. 

The question we decided to pose to initiate investigation is: Does the weight of the vinegar and baking soda mixture stay the same before and after you mix them?

We will elicit initial student ideas by asking students what they think will happen when we mix the two substances. Even if they have not done the experiment before, the investigation will be deepened because they will have to rethink their responses and why they think that. We will ask students if they think the mixture will weigh the same as the two separate substances, and if it changes to a solid or a gas would it still have the same weight?

The original weights of each substance on the zeroed out scale are:

  • vinegar: 41.5g
  • baking soda: 10.4g
  • plastic baggie: 5.1g
  • total weight before mixing: 57g
  • after mixing weight (in bag): 55.2g
  • after mixing weight (in beaker): 46.7g
Considerations/limitations: some air may have escaped when we first mixed the substances in the bag, not all of the mixture came out of the bag and back into the beaker to weigh after 

To decrease the human error, we can keep the two substances separate before the baggie gets closed so we don't lose any air. Once the bag is closed, we can mix the two and measure how the weight changes (or does not change). 

After the experiment, we can ask students: are these limitations enough reason that we lost that much weight? The change in the before/after mixing weight in the bag could be due to human error (not getting the bag closed quickly enough). 

To use evidence to answer the question, students can use the data/weights to see that the before and after weights are very similar in the bag, but when we transferred the mixture to the beaker we lost a lot of weight. This can be attributed to the gas being released from the bag and into the environment, so we lost the weight from its mass. 

I think I could use this in my future classroom to allow students to question the conservation of matter as well as their hypotheses before and after the experiment. One thing I might do differently/wonder if it would work better is if we had students measure the weight in the beaker first (they would see a lot of weight is lost) and then ask them where they think that weight goes. Then, we could have them try mixing it with the bag and ask them again where they think the weight went (they would see the weight is almost the same and the difference is that the air is caught in the bag). 



Comments

  1. BrookeMay 3, 2023 at 7:52 AM

    I definitely think that this would be a great way to teach kids about about how matter doesn't change when it changes form. I think it's a great critical thinking activity.

    ReplyDelete
  2. Meredith BourgeousMay 3, 2023 at 8:02 AM

    Using experiments like this in your future classroom can help students generate ideas about conservations of matter and interactions between matter. Having students use the evidence found in this lab to hypothesize what happened is a great way to get students thinking critically.

    ReplyDelete
  3. Taylor HospodarskyMay 3, 2023 at 6:40 PM

    I agree that this would be a great way to get students thinking about conservation of mass. It is very engaging, interactive, and informative for them.

    ReplyDelete

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