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Scheme of work – Cambridge IGCSE® Computer Studies (US) 0441
Unit 8: Organisation of data
Recommended prior knowledge
It will be helpful if students have studied Unit 6 before starting this unit.
Context
Students need to study this unit before or alongside Unit 12. For this unit, together with Unit 7, Computer Studies Support Booklet – Part 4
(http://teachers.cie.org.uk/docs/dynamic/31799.pdf) provides notes on section 4 of the syllabus and practice problems (with answers in Computer Studies Support
Booklet – Answers (http://teachers.cie.org.uk/docs/dynamic/31801.pdf).
Outline
The relationship between data and information; methods of data collection, encoding and preparation; appropriate methods of ensuring the correctness of data
(including validation and verification); methods of automatic data capture; analogue-to-digital and digital-to-analogue conversion.
File organisation: different forms of organisation and storage medium, depending on the data stored and the requirements for processing; sequential file processing
and processing individual records by means of record keys; sorting and merging; methods of processing and file maintenance.
Data types: numbers, characters, strings, arrays and the need for different data types and structures to represent the data for a particular application.
Syllabus
ref
Learning
objectives
4.2.1
The relationship
between data and
information
Collection of data
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Suggested teaching activities
Learning resources
Consider the Input, Process & Output model and introduce the idea of
information as appropriately presented processed data.
LWS coursebook pp. 30–1
www.teach-ict.com/ks3_old/unit9_1/miniweb/pg3.htm
Simple illustration of Input, Process & Output
It is helpful to distinguish between data collection prior to entry, often on
paper forms and methods of data capture (when data actually enter the
computer).
Students need to describe different data capture methods and learn when
their selection is appropriate:
Cambridge IGCSE Computer Studies (US) 0441
www.teachict.com/gcse/theory/datainfo/student/shome_datainfo.htm
Theory notes, activities and quizzes on data and
information (ignore knowledge for this syllabus)
LWS coursebook pp. 31 and 32–3
www.teachict.com/gcse/software/datacapture/students/shome_datac
apture.htm
1
Syllabus
ref
Learning
objectives
Encoding of data
for input
Methods of
ensuring its
correctness
(including
validation and
verification and
the distinction
between these)
Analogue-todigital and digitalto-analogue
conversions
Suggested teaching activities
Learning resources
•
•
Theory notes, activities and quizzes on data capture
manual input via keyboards and touch screens
automatic data capture techniques:
• barcodes in automatic stock control systems
• OMR techniques in input of lottery entries and survey data
• OCR techniques in input of text in questionnaires
• sensors in data-logging.
Explore the types of encoding used to help students describe encoding of
data and the reasons for its use.
Other forms of data preparation include ensuring that data are in a
standard format.
Explore web forms for examples validation and verification techniques and
ISBN codes as examples of ID codes with check digits, to help students
learn to describe and select:
• validation techniques (e.g. range checks, type checks)
• the use of check digits (how check digits are generated and why they
are used)
• verification techniques (e.g. double entry and visual checks) and their
uses (e.g. checking password entries).
Although spreadsheet software does not apply type checks by default,
students could perform practical exercises in both spreadsheet and
database software to apply a range of validation checks.
Consider how analogue (smoothly changing) data from a sensor (e.g. for
temperature, moisture or pressure) can be input as digital (step-valued)
data into a computer.
Explain that some sensors are effectively switches with digital outputs, but
most have analogue output requiring ADC to produce digital data for a
monitoring or control system.
LWS coursebook p. 31
www.teachict.com/as_a2/topics/data_info_know/datainfo/coding_of_
data.htm
Introduction to encoding data
LWS coursebook pp. 33–7
www.teach-ict.com/gcse/software/db/miniweb/pg10.htm
Introduction to validation
www.teach-ict.com/gcse/software/db/miniweb/pg11.htm
Introduction to verification
www.bbc.co.uk/schools/gcsebitesize/ict/databases/3datav
alidationrev1.shtml
First of two pages on data validation and verification
LWS coursebook pp. 31–2
www.teachict.com/gcse/software/control/miniweb/pg4.htm
Introduction to analogue-to-digital conversion
http://gcsecomputing.org.uk/theory/1_4/1_4_sound.html
Introduction to ADC and DAC for sound
Similarly, a monitoring or control system may only need to switch (or
rapidly pulse) an output to a lamp or motor, but when an analogue
(smoothly changing) output is needed, a DAC is required.
Consider a computer sound card as an example of a device containing
both sorts of converter and research other computers or devices requiring
one or both sorts.
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Cambridge IGCSE Computer Studies (US) 0441
2
Syllabus
ref
Learning
objectives
4.2.2
File organisation:
different forms of
organisation,
depending on the
data stored and
the requirements
for processing;
processing
methods
4.2.3
Data types for
numbers,
characters,
strings, arrays;
the need for
different data
types and
structures to
represent the data
for problems
being solved
Suggested teaching activities
Learning resources
Explore different ways in which a set of records could be stored in a file to
help students learn to describe:
• the need to process files
• file structure: field name, field type, concept of key field, relationship
between fields and records and conventional presentation in
spreadsheets and database tables
• file organisation:
• types of file: serial, sequential and direct (random) access
• their applications, e.g. serial file in a batch processing system,
direct access in real-time transaction processing system.
• how files are processed
• file maintenance: updating/amending, inserting and deleting data from
a file as appropriate, e.g. car sales business will insert data when a
new car arrives, delete data when a car is sold and amend data if
there is an error or they have a sale and reduce price
and select with reasons, the appropriate file organisation and processing
methods for a particular application.
Data types can be introduced by considering the different data types that
may be used in the various fields within a record.
LWS coursebook pp. 37–9
Students could perform practical work:
• on a sample database, to understand that a database program
prevents inappropriate data entry partly through the use of type checks
to distinguish between acceptable and unacceptable types of data on
data entry
• on a similar sample spreadsheet, to understand that:
• a spreadsheet program accepts any string of characters entered
into a cell and automatically interprets it as a particular data type,
with text as the default type
• some other data types can be enforced by applying appropriate
data validation to a cell, or range of cells.
www.teachict.com/gcse_new/databases/terminology/miniweb/pg7.ht
m
Introduction to key fields
www.cedar.u-net.com/ict6/demoidx.htm
Search for access to find direct and serial access
LWS coursebook pp. 39–42
www.teachict.com/gcse_computing/ocr/216_programming/handling_
data/home_handling_data.htm
Theory notes on data types
This should help students to:
• identify the different forms of data and explain how the data is
represented for processing
• explain the need for different data types and structures and how these
relate to the data of the given problem.
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Cambridge IGCSE Computer Studies (US) 0441
3