Thursday, June 7, 2012

30 min - Binary Baubles (K-8)


Students learn about representing numbers and letters in binary, as functions of on and off. At the end, we'll make magnets or bracelets with the students' initials in binary for them to take home.

Kindergarten Modification: Students will make bead & pipe-cleaner bracelets instead of refrigerator magnets.


ASCII Poster
Power Button Pictures
Picture of Computer Insides
Dissected Hard Drive or Picture

Kindergarten - 
4x6 paper in B&W
Pipecleaners (1 per student)
Pony Beads (8 of each in B&W per student).

Higher Grades - 
Display Grid
Duct tape squares
1" squares of quad graph paper (1/student)
1" self-stick epoxy resin square (1/student)
1" strip magnet square (1/student)


As the instructor, you will begin by thanking the class for letting you come visit.  It is very important that the instructor be pleasant and up-beat.

To warm up the room, the ask: "Who has seen a computer?"  This question gets the room buzzing and helps the children quickly gain a sense of confidence that they are already prepared for the lesson ahead.  In a few cases, there will legitimately be children who have *not* seen a computer, especially in kindergarten.  In those cases, don't overly praise those who have, but otherwise proceed in the same manner. Ask the following set of questions to get everyone's mind on the same page:

1)  Is a computer an animal?
Almost every child will say "no".  Shake your head and acknowledge that a computer is, in fact, not an animal.

2)  Is a computer a vegetable?
Children should be yelling "no" more confidently now.  Imagine having your parents telling you to "finish your keyboard or there will be no dessert!"

3) What *is* a computer?
At this point, children should be eagerly raising their hands.  You don't need to seek out a "correct" answer here, but listen to the types of answers they give you.  The farther away from correct that they are, the more likely it is that you're going to need more time at the end to help with the technical part of the activity.

Bring children out of the question/answer session by confirming that a computer is a machine.  Ask what they think they would see if you opened a computer up?  Are there magical monkeys inside?  Rocks with special powers?  No, but there *are* lots of cords and circuits which carries electricity from place to place. Tell them that a computer relies on electricity (through a cord or battery) to work correctly.

At this point, pull out SWITCH.PDF and show them page 1.

Ask the students if they've seen a switch like this before.  They will probably offer up some places that they've seen switches like that, or argue about the shape and color.

Share with them that this is an "On/Off" switch.  Describe how pressing the "1" turns electronics ON and pressing the "0" turns them off.  Ask them if that makes sense, and to really hit the point home, ask what position the button is currently in.  What would we do if we wanted to turn it off?

Next, show page 2 of SWITCH.PDF and ask if anyone has seen a button like this.  This one happens to be from an Xbox, but they may have seen one on their home computer or even in a fancy car.

Have them look really closely at the symbol in the middle.  Can they tell what it is?  It's a 0 with a 1 in it!  That's right, this button can turn something both on AND off by pushing in the same place.  Cool, huh?

If you feel like you will have time, you can show them a hard drive and explain how computers send on & off signals to magnetize and de-magnetize sectors.  Let them know that *that* is how information is preserved and not by saving words in English, Spanish, or pictorial form.  There is a benefit to having a physical hard drive for showing-off, in that you can really let the students see that there's no paper to write on and no compartments to "store" stuff.

Now that children get the relationship between 0&1 and on & off, tell them that you are going to introduce them to a special secret code, called "ASCII", that computers use to save and transmit information.  At this point, you can either project this ASCII.PDF onto the screen, or hang a printed poster version of it (I prefer to do both).

At this point, I like to ask if we have any "secret agents" in the room.  It puts a playful and adventurous mood into the atmosphere. Once the poster is displayed, explain to the room that the black squares are "off" and the white squares are "on".  Tell the kids that each letter is made up of eight squares (which we call "bits"), each is either on or off.  Let them know that a grouping of eight bits is called a "byte".  Chances are that several eyes will light up as they recognize the word.  You can help them along by mentioning "kilobyte", "megabyte", and "gigabyte".

The next thing we do is play a little surprise game.  If you're going to be making a magnet, start with an 8x1 grid of 2" squares and double-sided duct tape pieces (these are made by sticking the back of white tape to the back of black tape and cutting into 2" sections).

Tell the students that it's hard to demonstrate using an 8x1 grid, so you are going to move it to two rows and use a 4x2 - For this, you can cut the provided grid in half. This will help to prepare them for their final activity where they will be filling in squares on a 4x4 grid (I cut quad size graph paper into 1" squares for this activity).

For kindergarteners, you can demonstrate with beads on a pipe-cleaner (fuzzy wire stick).  I personally like to use a "bit-shelf" for large classrooms without a document projector.  It's made of foam-core board.  scored the long way, and folded into a pocket.  A couple of magnets in the back will secure it to a typical whiteboard.  I then indicate the bits with 4.5"x6.5" pieces of black and white paper.

In either case, you can show students how to represent the letter of your choice using the pattern on the poster.  Repeat as necessary.

Once you're comfortable that they're familiar with the method, tell them that you're going to leave the room while they choose their own letter.  Let them know that they have one minute to choose *and* have their teacher "code" it on the grid (or pipe-cleaner or bit-shelf).  Make sure it takes only about a minute, because you'll need the remaining 10 minutes for an activity.

Leave the room for one minute, then return.  They may, or may not, remove the ASCII poster.  To more easily guess the letter,  try to memorize 'P'.  The letter 'P' is the letter where the first nibble changes from 0100 to 0101.  That means you have a clean slate on the second nibble with 0000.  Therefore, 'P' is 01010000.  To figure out letters after 'P', you can ignore the 0101 and just translate the second nibble to decimal.  That way if they give you 0101 0011, you translate b0011 = 3 so they've chosen the 3rd letter after 'P', which is 'S'.

If the letter starts with 0100, there is a trick for that, too.  Invert the second nibble, translate, and count back from 'O'.  That means if they give you 0100 1111, you invert the b1111to b0000 = 0, so 0100 1111 is 'O'!  Along the same lines, if they give you 0100 0011, you invert b0011 to b1100 = 12, which means you count 12 back from 'O', giving the letter 'C'.  They'll think you're a mind-reader!

Once they have had fun trying out their coding/decoding skills, it's time to let them encode their own initials (I usually have all kindergarteners encode the same letter...maybe K?)  For those using a bit-board and/or fuzzy wire sticks, demonstrate the group's letter on the bit board for them, then walk around and help the class emulate it with beads.

For students making magnets, the process is just a bit longer.  Have each student choose their two favorite letters. Have them color the first 2 rows of their graph paper with the binary code for the first initial, and the second two with their last.  Let them know that mistakes are okay, and even if they mess up the letter that they were thinking of, the binary that they end up with does *something*.  This helps with confidence in getting started, and also helps conserve supplies by not re-doing items after a "mistake".

After the graph paper is colored, have them take one of the clear epoxy domes off of the backing and carefully stick it on to their graph paper.  Tell them to be cautious, because once it's on, it can't be peeled off without damaging their craft.

Finally, peel the paper off of the magnetic square and adhere it to the back of the graph piece.

Congratulate the students on a job well done and ask them if they had a good time.  This whole lesson should take around 30 minutes if you have an adequate number of room helpers (a teacher plus one?) slightly more if you are the only one available to troubleshoot during the craft.

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