IELTS Writing Task 1 Process Diagram: How Glass Is Recycled

The diagram below shows how used glass is recycled into new glass containers. Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words.

The process is linear, beginning with the collection of used glass and ending with the dispatch of new glass containers, and consists of six sequential stages:

Used glass items, such as bottles and jars, are collected from households through kerbside collection schemes or public bottle banks.
The collected glass is transported to a recycling facility, where it is sorted by colour into clear, green and brown batches, and any contaminants, such as metal lids, are removed.
The sorted glass is crushed into small fragments known as cullet.
The cullet is mixed with raw materials, including sand, soda ash and limestone, and fed into a furnace.
The mixture is melted at a temperature of approximately 1500°C to produce molten glass.
The molten glass is moulded or blown into new containers, which are cooled and then dispatched to manufacturers and shops.

Examiner notes: why this is a band 9 response

Task Achievement

The overview establishes that the process is linear and has six stages, and correctly summarises the general nature of the process (physical and thermal changes) before the detail is given; every stage (collection, sorting, crushing, mixing/melting and moulding/dispatch) is reported accurately and in the diagram’s order.

Coherence & Cohesion

The six stages are organised into three paragraphs of two stages each, with each paragraph forming a coherent unit (collection and sorting; crushing; melting and moulding), and cohesion is achieved through a range of markers (“begins when”, “then”, “once”, “subsequently”, “finally”) rather than one repeated connector.

Lexical Resource

The response uses precise, topic-specific vocabulary (“cullet”, “soda ash”, “moulded or blown”) and varies its reporting verbs across the six stages (“collected”, “transported”, “sorted”, “crushed”, “mixed”, “melted”, “dispatched”) without unnecessary repetition.

Grammatical Range & Accuracy

The passive voice is used accurately and consistently for a process performed by machinery rather than a named agent (“are collected”, “is crushed”, “is melted”, “are dispatched”), and non-defining relative clauses (“which are cooled and then dispatched…”) add grammatical variety without error.

Common pitfalls specific to this task

See commonMistakes above: the most damaging is skipping the colour-sorting stage, since colour separation is a distinct, necessary stage in the diagram and omitting it loses both accuracy and a full stage of the six.