maker faire and rain plans

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Last year, I blogged about co-organizing a booth at World Maker Faire and that we won a blue ribbon.  This year we won a red educators choice ribbon.  Which was also very cool.  Plus this year, my friend and I ran a whole tent.

It was a lot of fun and we got to see some from robots that the kids made.  Of course we had all the FIRST robots (FIRST Lego League, FIRST Tech Challenge and FIRST Robotic Challenge) that the students build.  But we also had a heat/motion sensitive hand sanitizer dispenser.  Especially helpful since we were next to the port-a-potties!

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Speaking of rain, our rain plans get better every year!  Let me tell you what happened this year.

Saturday 9:30am

Norm and I gave the morning briefing to the teams.  Which covered what to do if it rains.

  • move everything into the middle of the tent
  • cover everything electronic with tarp or painters plastic
  • leave a couple team members with the stuff and have everyone else go into the Hall of Science (you can only fit so many people in a tent)

Saturday 9:40am

It starts drizzling.  Luckily everyone was listening and was able to execute the rain plan.  And also luckily, the rain didn’t last long.  While we were waiting under the tent, Bronx Science added an umbrella to their robot. mf8

Saturday about 11am

More rain.  Again, everyone dealt with the electronics quickly and the rain didn’t last long.

Saturday 7pm

The prediction was for rain 8pm-midnight and downpours (.5 to 1 inch per hour) from midnight-6am.  Clearly we needed to protect the booth well.  We moved everything to the center, flipped tables over and covered the FTC field with:

  • painters plastic
  • a table cloth
  • a garbage bag
  • chairs to hold everything down

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Sunday 7:30am

I was first to the booth and was thrilled to see that our plan worked.  I had some students help me lift the plastic from the corners in.  Someone said it looked like a goldfish bowl – there was so much water inside.  But the tops of the foam mats were mostly dry.

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Sunday 6pm

While we protected the top of the field, we didn’t for the bottom.  It was fine, but I hadn’t realized how wet it was down there until we picked up the field!

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Improvement

The tablecloths worked better than I’d have ever imagined.  The painter’s plastic also worked really well.  And for FRC teams – “bag and tag” bags work wonders for rain protection – great idea Xavier!

What is the lesson?

Have good plans.  Communicate them.  Make them better year after year.

 

java puzzlers at the java sig

I got to see Josh Bloch and Bob Lee perform 9 Java Puzzlers.  That’s right.  I said perform.  They were funny, dynamic and had great banter.  It felt so natural.  And it was educational on top of all that.

I’m not going to try to transcribe the puzzlers.  You can read the book for many like this.  What I am going to do is mention my favorite 3 things I learned.

1) Double.MIN_VALUE isn’t what you think

Integer.MIN_VALUE is the smallest possible Integer.  So clearly Double.MIN_VALUE is the smallest possible Double.  Nope!  Double.MIN_VALUE is the smallest positive number that can be represented as a double.  4.9E-324.  Double.NEGATIVE_INFINITY is the smallest possible Double.

2) Compile time “constants” can change

System.out.println(Const.A + ” ” + Const.B);

If you compile and run this println against

interface Const {

String A = “a”;

String B = null;

}

it prints “a null”.

Then if you change it to run against

interface Const {

String A = “A”;

String B = “B”;

}

it prints “a B”.  That’s right.  The “a” is remembered because compile time constants are compiled in.  Whereas null isn’t a compile time constant so the new value is used.  Same for enums – not a compile time constant.

3) Autoboxing is a minefield

Ok.  So this one I knew already.  But it’s really important.  When comparing Integer objects, == is used.  Not autoboxing.  And JDKs are free to have the cutoff for where Integer objects are cached for autoboxing in different places.  So it is important not to rely on this.