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Grade 8 Light and Optical Systems

Mission Impossible

Our grade 8's have been trying to avoid our motion detectors this week in their study of how light is reflected, transmitted and absorbed by different materials. Our school has several motion detectors as a part of our alarm system, the students were challenged by their teachers to avoid detection. A motion detection light was also mounted in their classroom for testing.

Using the scientific process, students hypothesized what movements or materials would enable them to get close enough to the treasure (candy) without the motion light being triggered. Each pair of students had to devise and submit at least 3 different hypotheses and test them.

There was a large variety of costumes, props and materials brought in for the final testing on November 19, 2012. Students also submitted their hypotheses as evidence of their process in arriving at their strategy.

Student Hypothesis:
- I think that if I lie in the snow and walk up to the sensor with an umbrella, it won’t be set off. The umbrella will only be big enough for one of us so, I will have to crouch behind it and do a mini-man walk/run up to the sensor. I think this will work because the sensor is a thermal sensor, so changes of heat will set it off. If I am covered in snow (cooler than room temperature) than it might/might not work but I can make sure it works by using an umbrella that is around room temperature to block my movements.

-I think glass will work because glass is actually a liquid and liquids hold their heat really well. Since glass holds heat the best it will remain the same temperature as the background. Glass should work because it is dense therefore the infrared can not pass through it registering only the temperature of the glass instead of you behind the glass.


Garry McKinnon said...

Through this blog you highlight the Calgary Science School Exemplary Teaching and Learning dimensions relating to promoting learning through a disposition of inquiry and making classrooms thriving places of active research. You demonstrate how your students are authentically engaged in learning more about the transmission, reflection and absorption of light by developing hypotheses (conjectures) and testing them to determine their validity.

Anonymous said...

This is a really great idea, but how exactly did you assess and grade the students?

Cheng said...

For this particular project, the assessment was not based on success of failure of the student attempts, but on their hypotheses. For each hypothesis or attempt they made, they needed to include a "because" statement that related to what they knew about the different materials and how they interact with light. Many students felt they needed to go further by researching how the infrared sensor worked.

On a scale from 1-4 here was the general breakdown
1-a prediction with a because statement
2-an implementation of design that matched their hypothesis, a prediction with a because statement.
3-an implementation of design that matched their hypothesis, a prediction with a because statement that included language from their learning.
4-a prediction with a because statement that included language from their learning, life observation and an implementation of design that matched their hypothesis.

Good luck!

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