Physical Science: Session 4
Describe a New Substance; EDC Insights
at a Glance:
Curriculum: EDC Insights, The Mysterious Powder, Kendall-Hunt Publishers
Grade: Upper elementary
Topic: Learning Experience 10: Using Science Skills to Describe a New Substance
Prior to this lesson, Rebecca’s class had been working for four weeks, investigating the different mystery powders, and trying to identify them by observing their properties during various chemical reactions.
In Rebecca’s adaptation of this lesson, the class took two substances that they were familiar with, baking soda and vinegar, and mixed them together. “They knew that there was going to be a chemical reaction,” says Rebecca, “but we took it a step further and put them into a closed container and weighed them before and after they were mixed, to see if the matter would be conserved.”
The first time the students did the experiment, they put a balloon over the top of the bottle in which the reaction occurred, so they could watch the newly created gas fill the balloon. When the class weighed their bottles afterwards, however, several students found that their bottles weighed less than they had before the reaction took place. Thinking that either the balloons had small holes in them or that the seals were leaky, Rebecca rethought the experiment and had the students replace the balloons with the bottle caps.
She recounts, “This time the students found that the substances weighed the same before and after they were combined, even though some of the matter disappeared from view. And I think it’s important that students realized that, sometimes in science when you do an experiment, it doesn’t always go the way you expect.”
After this lesson, Rebecca did several follow-up lessons where the students investigated conservation of matter through other chemical reactions. “It’s kind of a hard concept,” she said, “because if you watch a piece of wood burn, it seems to be gone. So, the idea is to get students to understand that it’s not gone; it’s just changed its form.”
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