New nameserver

Finally got the nameserver replaced today, after several days of struggle spread over recent weeks. I used a Raspberry Pi running Debian Stretch, which, though it may sound under-powered, is actually running at a clock-speed 1.5 times the old server, which was a re-purposed thin client. Our small domain has a very light DNS load, but I prefer to have it running on its own box, and not to have all the critical eggs in one basket.

Anyway, I struggled a bit to get the zone files served correctly, since a few things had changed since the old server. At first named was failing to start, and then I was getting SERVFAIL errors on authoritative lookups. I learned new things and have a better understanding of dns, systemd, and iptables after this experience.

Test Web Server

Using a Raspberry Pi with Minibian Jessie Install:

mysql-client mysql-server postgresql apache2 php5 libapache2-mod-php5 php5-mysqlnd php5-curl php5-gd php5-intl php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-pspell php5-recode php5-snmp php5-sqlite php5-tidy php5-xmlrpc php5-xsl php5-pgsql php5-apcu phpmyadmin phppgadmin

The While-loop Game

Last week I introduced a while loop to my cryptography class, and it was used for the first attempt at encryption (a simple reverse cipher). Since this is such a crucial concept, and absolutely vital to further and unavoidably more complex algorithms to come, I wanted to reinforce it with a hands-on activity.

The While Loop Game

Game is a misnomer, but it got their attention and they didn't complain, so it worked this time!

I created some paper cards, and also an electronic version of the game. Actually only round 1 exists on paper so far. Round 2 has to be on the computer.

Everything is in this file, electronic game and paper game to print and cut up:

while_loop_game.odg

How to Play

The While Loop Game involves constructing a while loop by arranging cards, either physically or on the computer. Here is how to play:

1. The paper is the programming editor. The solid line represents the left margin. The dotted line represents a 4-space indent.
2. With your partner, arrange the cards to make a working while loop. You won't need all the cards. Partners must explain their ideas and run through the loop together to make sure they agree how it works.
3. Write the output of your program, in order, into the output box.
4. Check your answers to see if you won.

The Outcome

The game went very well, and really improved the confidence of some of the teams (they worked in pairs). Of the 12 pairs of students, three could build a working while loop without any comments from me, and the rest could do it with just a little help here and there. In the more difficult round two, only one team could get it unaided, but several followed after a few hints. Only one team was still far away from the solution when I revealed the answers.

Actually several teams pro-actively started typing their programs into codeskulptor to check them, which I hadn't expected, and was nice to see.