CS Unplugged activity
Secret Messages in ASCII
Computers do not store letters. They store numbers. ASCII is the code that turns each letter into a number, and you are about to crack it.
Your code table
| A | B | C | D | E | F | G | H | I |
|---|---|---|---|---|---|---|---|---|
| 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 |
| J | K | L | M | N | O | P | Q | R |
| 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 |
| S | T | U | V | W | X | Y | Z | space |
| 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 32 |
What to do
- Find each number in the table above.
- Write the matching letter in the box under it.
- A hatched box is the code 32. That means “space.” Leave it blank.
- Read your finished answer to check it makes sense.
Now decode these
1. A computer stores every letter as a ___.
78
85
77
66
69
82
2. Binary only uses two digits: zero and ___.
79
78
69
3. A group of eight bits is called a ___.
66
89
84
69
4. Fun fact: the first computer bug was a real ___.
84
73
78
89
32
77
79
84
72
Write your name in ASCII
Now go the other way. Write one letter of your name in each top box, then use the table to write its code underneath.
Short name? Leave the extra boxes blank. Longer than eight letters? Keep going on the back of the page.
Want the whole table, with lowercase letters and punctuation too? See the full ASCII / Hex table.
Answer key
- NUMBER
- ONE
- BYTE
- TINY MOTH
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