### Digitech lesson 3-Binary!

**Goal:**

I understand the counting system of binary and why computers use it.

**APK:**

WHAT ARE CODES? Name some- explain them to your partner

What’s the point?

**New Information:**

Quickly review meanings of **data** and **information**.

Binary is a way to communicate data & information when the only thing you can do is switch on or off- so it’s not a code to keep things secret, but one that makes use of a the limited capabilities of a computer- basically all it can do is switch on or off (Lucky it can do it AMAZINGLY QUICKLY!)

So….how does it work?

Take notes & discuss

Basically it uses a different place value system- instead of base 10 (where there are 10 different symbols and we move up to the next place value when we get to 10 times the value of a unit/one, and shifts a place value whenever it gets to 10 times bigger), Binary is a base 2 system-it only has two symbols (representing off-0 or on-1)

Watch this & discuss:

(mistake at 1:24- she means “1 X 2” not “1 X 1”)

Another explanation if you’d like:

**What’s it all about?**

Computers today use the binary system to represent information. It is called binary because only two different digits are used. It is also known as base two (humans normally use base 10). Each zero or one is called a *bit *(**b**inary dig**it**). A bit is usually represented in a computer’s main memory by a transistor that is switched on or off, or a capacitor that is charged or discharged. When data must be transmitted over a telephone line or radio link, high and low-pitched tones are used for the ones and zeros. On magnetic disks (floppy disks and hard disks) and tapes, bits are represented by the direction of a magnetic field on a coated surface, either North-South or South-North. Audio CDs, CD-ROMs and DVDs store bits optically—the part of the surface corresponding to a bit either does or does not reflect light. One bit on its own can’t represent much, so they are usually grouped together in groups of eight, which can represent numbers from 0 to 255. A group of eight bits is called a byte. The speed of a computer depends on the number of bits it can process at once. For example, a 32-bit computer can process 32-bit numbers in one operation, while a 16-bit computer must break 32-bit numbers down into smaller pieces, making it slower. Ultimately bits and bytes are all that a computer uses to store and transmit numbers, text, and all other information. In some of the later activities, we will see how other kinds of information can be represented on a computer.

**Application:**

For this activity, you will need a set of five cards, as shown below, with dots on one side and nothing on the other. Choose five children to hold the demonstration cards at the front of the class. The cards should be in the following order:

**Discussion**

What do you notice about the number of dots on the cards? (Each card has twice as many as the card to its right.)

How many dots would the next card have if we carried on to the left? (32) The next…?

We can use these cards to make numbers by turning some of them face down and adding up the dots that are showing. Ask the children to make 6 (4-dot and 2-dot cards), then 15 (8-, 4-, 2- and 1-dot cards), then 21 (16, 4 and 1)…

Now try counting from zero onwards.

The rest of the class needs to look closely at how the cards change to see if they can see a pattern in how the cards flip (each card flips half as often as the one to its right). You may like to try this with more than one group.

When a binary number card is not showing, it is represented by a zero. When it is showing, it is represented by a one. This is the binary number system.

Ask the children to make 01001. What number is this in decimal?

What would 17 be in binary?

Try a few more until they understand the concept.

Make a binary table:

Cut out the cards on your sheet and lay them out with the 16-dot card on the left as shown here:

Make sure the cards are placed in exactly the same order.

Now flip the cards so exactly 5 dots show—keep your cards in the same order!-

represent this with a 0 when it’s blank and a 1 when there’s a number- so how do you write 5 in binary?

Find out how to get 3, 12, 19.

Is there more than one way to get any number?

What is the biggest number you can make? What is the smallest? Is there any number you can’t make between the smallest and biggest numbers?

Extra for Experts: Try making the numbers 1, 2, 3, 4 in order. Can you work out a logical and reliable method of flipping the cards to increase any number by one?

Binary decoding game- http://games.penjee.com/binary-numbers-game/

Next level up- http://games.penjee.com/binary-bonanza/

**Goal Reflection:**

What are some interesting things you noticed about the binary counting system?

What are the advantages and disadvantages of using binary?

Share reflections