Why compression is needed: less storage space

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Quick Questions

Shade in the A or B circle for each question.

1. A phone has 64 GiB of storage. Which statement is true about compressing its photos?

A Compressed photos are larger, so fewer of them fit on the phone

B Compressed photos are smaller, so more of them fit on the phone

2. Which is a reason for compressing a file to save storage space?

A The file takes up more space but loads faster

B The file takes up less space on the device

3. A music app stores 1000 songs. If each song is compressed, what happens to the total storage needed?

A It goes down

B It goes up

4. A company stores millions of images on its servers. How does compression help with cost?

A Less storage needs to be bought, so costs are lower

B More storage needs to be bought, so costs are lower

5. A photo is 8 MiB uncompressed and 2 MiB compressed. How many compressed photos fit in 80 MiB?

A 40 photos

B 10 photos

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Uncompressed: 20 MiB, Compressed: 5 MiB		ADividing the storage by a file size gives how many files fit on the device.
264 GiB / 4 GiB = 16 files		BThe storage saved is found by subtracting the compressed size from the original size: 20 - 5 = 15 MiB, not by adding.
3Compression makes each song smaller, so more songs fit on a phone with 8 GiB of storage.		C8 GiB / 4 MiB = 2048 songs
4Compression saves storage space, so a smaller and cheaper storage device can be bought.		DSaved space = 20 MiB - 5 MiB = 15 MiB
5Compression makes files bigger, so fewer photos fit on a phone.		ECompression makes files smaller, not bigger. Smaller files mean more photos fit on the phone.
6Compressed 5 MiB file + 20 MiB original = storage saved 25 MiB		FThe compressed file is four times smaller, so it uses only a quarter of the storage space.

Definitions

compression saves storage

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF compressedSize _ originalSize THEN

OUTPUT originalSize _ compressedSize

OUTPUT freeSpace ___ compressedSize

IF compressedSize < originalSize ____ OUTPUT "More files fit" ENDIF

OUTPUT saved _ originalSize * 100

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A storage = 64

B photo = 4

C compressed = 1

D count = storage // photo

E print(count)

Question 2

A # Compressed files are larger

B song_mb = 6

C small_mb = 3

D print(song_mb - small_mb)

Question 3

A IF compressed > original THEN

B OUTPUT "More files fit"

C ELSE

D OUTPUT "Fewer files fit"

E ENDIF

Question 4

A photo_mb = 5

B small_mb = photo_mb * 5

C print(small_mb)

Question 5

A cost = 2

B big = 100

C small = big * 1.4

D print(small * cost)

Answer Key

Why compression is needed: less storage space

Section A: Quick Questions

B — Compressed photos are smaller, so more of them fit on the phone

B — The file takes up less space on the device

A — It goes down

A — Less storage needs to be bought, so costs are lower

A — 40 photos

Section B: Match the Pairs

Uncompressed: 20 MiB, Compressed: 5 MiB → The compressed file is four times smaller, so it uses only a quarter of the storage space.

64 GiB / 4 GiB = 16 files → Dividing the storage by a file size gives how many files fit on the device.

Compression makes each song smaller, so more songs fit on a phone with 8 GiB of storage. → 8 GiB / 4 MiB = 2048 songs

Compression saves storage space, so a smaller and cheaper storage device can be bought. → Saved space = 20 MiB - 5 MiB = 15 MiB

Compression makes files bigger, so fewer photos fit on a phone. → Compression makes files smaller, not bigger. Smaller files mean more photos fit on the phone.

Compressed 5 MiB file + 20 MiB original = storage saved 25 MiB → The storage saved is found by subtracting the compressed size from the original size: 20 - 5 = 15 MiB, not by adding.

Section C: Definitions

compression saves storage — Compressed files are smaller, so they take up less storage space. This means more photos or songs fit on a device, and less storage needs to be bought.

Section D: Fill in the Blanks

IF compressedSize < originalSize THEN

OUTPUT originalSize - compressedSize

OUTPUT freeSpace DIV compressedSize

IF compressedSize < originalSize THEN
  OUTPUT "More files fit"
ENDIF

OUTPUT saved / originalSize * 100

Section E: Spot the Error

D — The number of files that fit is found by dividing the storage by the compressed size (compressed), not the original photo size. It should be count = storage // compressed.

A — Compression makes files smaller, which is why they take up less storage space. The comment should say smaller, not larger.

A — More files fit when the compressed size is smaller than the original size. The test should be compressed < original.

B — Compressing the photo to one fifth of its size means dividing by 5. Multiplying would make the file bigger. It should be small_mb = photo_mb / 5.

C — A compressed file is smaller than the original, so it must be less than 100. Multiplying by 1.4 makes it bigger. It should be small = big * 0.4, which gives 40.