Astronomy students using adding machine paper to scale out the solar system using 10 cm = 1 AU. They soon figured out that the Oort Cloud would be nearly 3 miles away!
OK. I got your attention. Today in IS I we started the chapter on atomic structure and bonding with an ENGAGE activity focusing on electrical conductivity. Four solutions were tested using a crude conductivity device (light bulb) for qualitative data and a conductivity probe for quantitative data. We all had to look up microsiemens/cm as the unit for electrical conductivity! The cards in front of the beakers are mixed up on purpose as we figured out what was in each beaker. We discussed the danger of electrical devices near water and how the body makes the solution salty.
IS I students used the whiteboards today to show me (and themselves) that they understood the osmosis that was taking place in their model cell membranes. With a little prodding, the diagrams revealed some misconceptions and then understanding.
IS II students used the whiteboards to take the “texting” challenge. I returned, and we reviewed, the last quiz that they took in the chemistry unit and we are about to work with motion detectors tomorrow so this made for a great “bridge” activity. The first class really got into it and did a nice job. Thanks to Frank Noschese for the idea!
Astronomy students spent a few minutes outside collecting data for measuring the sun’s diameter. They projected an image of the sun onto mm graph paper and measured the image’s diameter. They knew how far apart the pinhole was from the image. They were also given the distance to the sun. Using the properties of similar triangles they were able to calculate an approximate diameter of the sun. Today’s value was 1.2 million km. Not bad given our method!
The IS I students had to identify 6 of the above unknown samples using density as the primary physical property. They used water displacement to find the volume and electronic scales to find the mass. Great activity as many of the substances were plastics that had densities that were very close. Accuracy was very important.
Galileo would be proud as IS II students do an activity “similar” to his inclined plane experiment. The real rationale is to have the students plan and conduct an investigation with a clear independent (angle of ramp) and dependent variable (time), a set of constants, reliable data, some calculations, a procedure, a materials list, a hypothesis, an analysis section that includes a graph done with Logger Pro, and a conclusion. I give them the “bones” of the report on a shared Google doc and they make it their own. They must insert at least one photo. They worked on the first lab report collaboratively and for this one they work as a group but write up the report on their own. By the way – thank you iOS7 for a stopwatch that now records to the 0.01 seconds.
A quick discussion of speed vs velocity and off we go to time how long it takes cars to pass between two trees 14 meters apart. Students then calculated speed in m/s and then converted to mph. After one lengthy factor label problem I showed them that 1 m/s ~ 2.24 mph. This is in preparation for a ball and ramp lab that closely mimics Galileo’s inclined plane experiment.