# 4. Binary coding

In this exercise, students will:

• convert letters to binary code
• and convert binary code to letters!
• save information.

## STEP 1

### Preparation

Print the work sheet for each student duo.

## STEP 2

### To work!

Do you show your students the inside of a desktop computer? (A photo on the IWB is also good enough!) Do they know where the computer stores the information? The hard drive or memory.

A computer does this in "code language": with ones and zeros. So everything has to be converted to 1 or 0. Also what we type. There is a table for this: each letter has its own secret code of 8 ones or zeros.

Do you project the work sheet onto the board? Have your students put you to work and write the letters they say on the board in binary language.

Take the work sheet now. It has the entire alphabet on it with the correct binary codes next to it.

Have your students look up which code goes with the first letter of their name.

Let them convert the binary code into areas of color: the ones become a black area, the zeros remain a white area.

Then take work sheet 2. Now we work the other way around: we start from binary code. Who can translate the code?

## STEP 3

### Discussion

Do you still know the code language? (morse code!)

Why would a computer prefer to work with ones and zeros than with letters and numbers?

Information is transported in the form of electricity in a computer. And that can only be “on” (1) or “off” (0). All information in a computer must therefore be stored in binary form. In a hard disk that information is stored magnetically: positive or negative. On a CD or a DVD, the information is stored as “reflective” or “non-reflective”

# Challenge!

Who can convert short words into binary language?

Who can decode your binary code