# Day 161: How Tall?

Tuesday, 29 April 2014

Not a lot of patience in this crowd for figuring out iPhone apps that measure the height of distant objects.

I took one group outside today to measure the height of a flagpole. We’re prepping for our Six Flags trip on Friday, where I’ll ask them to measure the height of several rides using iPhone/Android apps. This group was frustrated trying to read directions for apps they found confusing. For what it’s worth, I like iHypso Lite. Other teachers prefer their kids use the law of sines like so:

Applying the Law of Sines to measure a height (from our pre-Six Flags day packet).

# Day 160: Rocket Powered

Monday, 28 April 2014

An assortment of rockets.

The big project in the momentum unit is rockets. We build a rocket, estimate how fast it’ll go, and how high it’ll fly (using the Impulse-Momentum Theorem). Today, in addition to testing two classes, I showed others how to calculate for max speed and height.

I think we made a bunch of assumptions that over simplify the physics too much, so I doubt the accuracy of our calculations. It’ll be about two weeks before we actually launch, so I’m kinda chomping at the bit to test my calculations.

# Days 141-159

Tuesday, 1 April to Friday, 25 April 2014

Robotics almost always means Ultimate Frisbee and this trip was no exception. Here’re the best Frisbee players in the land!

Aw heck, I fell behind and the backlog was starting to feel too burdensome to ever overcome. Then I just decided to archive these days. I did stuff. Some of it was cool. Plenty of it was boring. There was a national championship robotics competition in there. Now we’re to today.

Note to my future self: just focus on the picture. It’s the part people really come for anyhow.

# Day 140: Clever Hack

Monday, 31 March 2014

We’re doing the accident investigation lab and one group has hit the end of their scale. They go over to the bucket of spring scales and instead of swapping out for a larger scale, they grab another of the same size. After a little testing, they realize that two scales pulled in parallel can be added to get the force being applied. Clever kids.

# Day 139: Accident Analysis Lab

Friday, 28 March 2014

Part I: Design an experiment to determine the coefficient of friction between a tire and the road. My students already completed a similar lab with different equipment, so they should be recreating that lab here.

Part II: Analyze some information about road conditions to recommend a safe speed limit for the road. Students need to combine Newton’s Second Law and kinematics to solve this problem. They also must be more fluid with working in different systems of units (miles per hour and meters per second gets ’em every time!).

Part III: Analyze the details of an auto accident to determine if the driver is lying about obeying the speed limit.

Get the entire accident analysis lab: Word format

# Day 138: FIRST Regional Action

Thursday, 27 March 2014

A mix of kids who were manning our internship linking service table on Thursday.

Our lead coder shows off Wilson. That’s what happens when your robotics kids get snow days and work from home for 3 days in a row.

It’s a beast!

The WiredCats (FRC team #2415) competed at the Peachtree Regional today. Well, today was practice matches and inspection day — we did both! I’m impressed with our autonomous routine that can now almost always score two balls in the 10 second period. Meanwhile, I’m unimpressed at the inconsistency of our shooting, which I chalk up to the thick rubber tubing that provides the catapult with its oomph.

I was out of the classroom all day with the robotics team, though the arena is only about 5 miles from school so I can still return tomorrow for classes. My students, meanwhile, started a lab that asks them to analyze a traffic accident scene using what they know about forces and friction. More on this lab tomorrow.

Also, we recorded this message for our school:

# Day 137: Video & Presentations

Wednesday, 26 March 2014

I volunteered my 6th period class to be part of a school promotional video. Above, the viedographer and director help the kids look natural while wearing the safety glasses they’ve never seen before (but look sufficiently science-y to go on) and the lab materials they won’t use until tomorrow. Apparently, fake it till you make it isn’t something these kids know about.

Meanwhile, 7th period finished their classwork and presented one problem. We had a sheet of ~5 force problems. I asked every kid to draw the free body diagram for each and solve one problem that I assigned them. Groups of two presented their one problem to the class. As usual, I was disappointed with presentations and am prepared to abandon them again for the foreseeable future because the kids goof off too much. Ugh, I know the value of practicing communicating your knowledge but can’t bring myself to “waste” class time on this goofing. I know that I need to figure out a better way to develop communication skills.

# Day 136: Crate Assembly Day

Tuesday, 25 March 2014

The robotics team won a spot at world championships at the Dallas Regional. Even though that’s about a month away, we began a major preparation today by assembling our shipping crate. The assembly team consisted of 2-3 underclassmen and one of our team leads. We’ll be competing at the Peachtree Regional this coming weekend, so the crate will wait for another week before getting a robot inside.

# Day 135: The Elevator Problem

Monday, 24 March 2014

I might have crammed every one of my classes today inside the building elevator to test how apparent weight changes when the elevator accelerates. Fortunately, my classes are small in numbers (biggest is 16) and in size (we were getting close to the elevator’s weight limit!), so we could all fit at one time — making the experience all the more fun.

We used spring scales and lab masses. Kids almost immediately observed that the weight changed when accelerating and returned to normal when the elevator was moving at constant velocity.

# Day 134: Vector Direction

Friday, 21 March 2014

Reporting the direction of a net or equilibrium force is quite the challenge for many of my kids because I require them to state the angle in standard position. Part of the problem, I know, is due to their geometry teachers teaching them the bearing system of measuring angles. For some reason, shifting the location of 0º and measuring CCW instead of clockwise just messes with these kids’ heads.

The other issue is not keeping it clear what the question is asking. Above, I ask students to find the direction of an equilibrium force. Without a good diagram, about 60% of my kids will screw it up about 80% of the time. Here’s a great example (look at #1).

For some reason, she thought that the equilibrium force would be 90º away from the net force, as she so eloquently explained in pencil on #1.

While we’re looking at it, check out how none of her diagrams include vector arrows showing direction. It keeps messing this one student up yet she won’t add the arrows to her drawings.