Years 7–8 Data & Information Definitions Worksheet: Representing data with binary and Acquiring, storing and validating data (Modules 9–45)
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Key terms
Write what each term means, in your own words.
1
8-bit binary: 128 64 32 16 8 4 2 1
2
subtract place values
3
2^n
4
ASCII
5
Unicode
6
resolution
7
sample rate
8
width x height x bits per pixel
9
$B$1
10
primary key
Answer Key
Years 7–8 Data & Information · Modules 9–45 · Student wording will vary for definitions
18-bit binary: 128 64 32 16 8 4 2 1 — A byte has 8 bits with place values 128 down to 1. Add the place values that are 1s. The smallest number is 0 and the largest is 11111111 = 255, so a byte stores 0 to 255.
2subtract place values — To write a number in 8-bit binary, go from 128 down to 1. If the place value fits in what is left, write 1 and subtract it. If not, write 0. Check by adding the place values.
32^n — The number of different values n bits can store. Each extra bit doubles it: 1 bit gives 2 values, 2 bits give 4, 3 bits give 8, and 8 bits give 256.
4ASCII — A standard table that gives every character a number, such as A = 65 and a = 97, so computers can store text as binary. Lowercase codes are 32 more than capitals.
5Unicode — A system that gives every character a unique number, including letters from many languages and emoji, so it covers far more than the small ASCII table.
6resolution — The number of pixels in an image, given as width x height (like 1920 x 1080). More pixels give more detail but make a bigger file.
7sample rate — The number of sound measurements taken each second, in hertz (Hz). CDs use 44,100 Hz. A higher rate gives better quality but makes a bigger file.
8width x height x bits per pixel — The size of an uncompressed bitmap image in bits. Multiply width by height by the bits used for each pixel, then divide by 8 to get bytes.
9$B$1 — An absolute cell reference. The $ before the column letter and row number locks the cell, so the reference does not change when the formula is copied. Press F4 to add the $ signs.
10primary key — A field whose value is different for every record, such as a student ID or an AutoNumber, so each record can be identified. Names make a poor key because two people can share one.