Day 2.38 Unbalanced Force Ranking Task

Wed. March 26, 2014

 

Physics students were given the task of analyzing several similar but different unbalanced force situations.  I had two of these types of problems so I decided to split my large class into just two halves.  This left 2 groups of 8-9 students each.  I gave the groups the assignment of coming up with 1 whiteboard for the group that every one in the group agreed on.  For a task like this that takes some thinking and debate the large groups worked really well to encourage discourse among the students without my interaction.  It was like having two small board meetings going on at the same time and I wasn’t involved in either one!

Day 2.37 Using Google Forms to Share Data

Tues. Mar 25, 2014

After groups made observations from the Sticky Tape Lab they shared their data with me and the class using a Google Form that looked like this:  (Link)

 

The class data then gets dumped into a Spreadsheet:  (Link)

And finally as a class we look at all the groups data in displayed as one nice summary format generated by Google: (Link)

This works as a great way to quickly, easily, and without too much debate, agree on what we should be seeing.  Because in this particular lab I’m not looking for a lot of debating discussion about what the data is.  We are able to spend our time analyzing the patterns in the data the way each group should be seeing it.  (Trying to have students draw conclusions from one set of wrong data doesn’t work too well, I’ve found that this fixes that.)

Day 2.36 Sticky Tape!

Mon. Mar 24, 2014

 

Classic Modeling Chemistry!  My chem students began exploring electrical interactions (granted we didn’t call them that yet.)  We used the traditional Scotch tape lab to statically charge the items and test their attraction and repulsion to each other.  This lab sets the table for creating a particle model that contains charge.  This will lead us into reasoning how compounds are bonded together.

Day 2.35 Claim, Evidence, Reasoning

 

Last week at the WSST (Wisconsin Society of Science Teachers) conference there was lots of talk about the Claim, Evidence, and Reasoning format for summarizing lab results.  I’ve always kind of tried to get students to write conclusions in this format, but never really had the simple defining model to aid them in their writing.  Today physics groups were creating whiteboards summarizing their results from the Unbalanced Force Lab, so I figured I would give it a try.  We’ll see how it goes.

Day 2.34 Plane Mirror Fun

Thurs. Mar 20, 2014

This is one of my favorite yet simplistic labs we do.  Using a small plane mirror students place a whiteboard marker in front of the mirror.  Because the markers are taller than the mirrors I have the students place a second marker at the location the image appears to be at.  Once they have it placed they measure the position of the “image marker” relative to the mirror, both x and y components.

The Setup:

 

The View in the Mirror:

Day 2.33 Unbalanced Force Lab

Wed. Mar 19, 2014

Yesterday Physics was brainstorming ideas about how to change the amount of unbalanced force on a system and then measure how that effects acceleration.  One group really wanted to “funnel” down the wind from a blowing fan cart.  Yesterday’s design looked good but ultimately didn’t help us.  The funnel didn’t allow enough air to pass through, most of the air just rebounded off the funnel and back towards the fan.  A couple of crude paper funnels worked a little bit, but they found having a funnel really didn’t change anything in terms of the force the cart was experiencing.  They scrapped the idea and simplified their approach.

What most groups ended up with was something like this:

Some decided to alter the mass of the cart and keep the fan speed the same.  Others are holding the mass constant and altering the speed of the fans.  To do this I have the fortune of having these sweet Fan Carts from Pasco:

Day 2.32 Fan Cart Question

Tues. Mar 18, 2014

Today we brainstormed variables that might affect the acceleration of an object that is experiencing an unbalanced force.  One group wondered what would happen if we were able to “funnel” the wind being blown from the cart down.  They hypothesized that the faster moving air at the end of the funnel would provide more “push” on the cart.  However, one of the group members saw a problem with the fact the air is pushing in a smaller area.  They began by trying to create a paper funnel without too much luck.  One found this nice plastic funnel in my chem equipment drawers.

They had a few problems with this set up.  Do you know what they were?  They are thinking of doing some modification to the design, so I’ll wait to share tomorrow what they come up with.

Day 2.31 Heating Mg Ribbon

Mon. Mar 17, 2014

Chemistry students heated magnesium ribbon in a crucible today.  By measuring the mass of the magnesium ribbon before heating and after we will make some predictions about what the reaction.  We will also use the data to determine the percent composition of the product as well as the empirical formula.  I believe using lab data to enforce the importance of mass and mole relationships is vital to student understanding.

Day 2.27 CAM Challenge

Tues. Mar 11, 2014

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Physics students were given a variety of challenges today.  One was to drop a marble from a designated height so that it would land in the cart approaching on the ground below.  As you can see above this group did quite well.

Day 2.26 Lens Lab Data – Call for Help

Thurs. Mar 6, 2014

 

Physics 2 students were given the freedom to investigate anything they felt compelled to using a light source, converging lens, and viewing screen.  Some groups choose to measure the distance from the light to lens and compare to the distance from the lens to image.  This was good, and the data modeled the Lens Equation  (1/do + 1/di = 1/f ) perfectly!

The above group (and one other one) choose to measure the distance from light to lens vs. the size (height) of the image produced.  The board above shows their data.  The raw data shows an inverse relationship.  So we decided to graph y vs. 1/x, this straightened the data out, so good, right?  Now comes the tough part.  What is the data modeling for us?  Here is where we are stuck.  One thing to keep in mind the focal length of the lens used is 15.0 cm.  (BTW, the other group used the same focal length lens and ended up with similar data.)

do = (14.67cm^2)(hi) + 14.91 cm

From what I can figure the y-intercept is the focal length of the lens, because you would get a image of size 0cm if the light was at the focal length of the lens.  BUT, what is the slope indicating?  What is with the units of cm^2?  Is it a coincidence that this number is also close to the focal length, or is it something significant?  What are we missing here.  Any and all help will be appreciated.  Please comment below or tweet me @MrBWysocki.

Thanks for the help!