Academic Writing Task 1 · line graph

The impact of different sugars on mouth acidity and tooth decay: IELTS Writing Task 1 sample answer

An IELTS Writing Task 1 line graph question with a Band 8 sample answer, the chart redrawn with its data, the vocabulary that lifts the report and how to write about line graphs.
  • 180 words
  • Line graphs
  • Academic
  • 20 minutes

The question

Eating sweet foods produces acid in the mouth, which can cause tooth decay. (High acid levels are measured by low pH values).

Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words.

Acid level in mouth from consumption of sugar/honey (pH level)
0246810Moment eaten5 minutes10 minutes15 minutes20 minutes25 minutes30 minutes35 minutes40 minutes
  • Fruit sugar
  • Cane sugar
  • Honey
View the data
Moment eaten5 minutes10 minutes15 minutes20 minutes25 minutes30 minutes35 minutes40 minutes
Fruit sugar74.24.95.25.566.877.1
Cane sugar73.63.94.54.64.95.36.27.1
Honey74.84.85.66.677.17.17.1

Chart redrawn by BandLadder from the data in the original IELTS practice task. Many IELTS practice tasks come from the Cambridge IELTS series (Cambridge University Press & Assessment); all rights in the original tasks remain with their owners.

Model answer

Band 8 sample answer

Band 8180 words. Every figure in the answer comes from the chart above.

The line graph illustrates the fluctuations in mouth pH levels over a 40-minute period following the consumption of three different types of sugar: fruit sugar, cane sugar, and honey. A pH level of 5.5 serves as the threshold, below which tooth decay is likely to occur.

Initially, all three substances start at a neutral pH of 7. However, within five minutes, acidity levels spike significantly for all types. Cane sugar causes the most dramatic drop to 3.6, followed by fruit sugar at 4.2 and honey at 4.8. Notably, all three substances fall below the critical 5.5 threshold within the first five minutes, indicating an immediate risk of tooth decay.

Regarding recovery, honey exhibits the fastest return to neutrality, rising above the 5.5 threshold by the 15-minute mark and reaching 7 by 25 minutes. Fruit sugar follows a more gradual recovery, crossing the threshold at 20 minutes and returning to 7 by 35 minutes. Conversely, cane sugar remains the most harmful, staying below the 5.5 threshold for 30 minutes before finally recovering to 7.1 by the end of the 40-minute period.

Write your own report and get a band

Take a timed Academic writing test and get a band for task achievement, coherence, vocabulary and grammar, with the sentences to fix.

Write a report, get a band free →

Line graphs

How to write about line graphs: tips and vocabulary

  • →Overview first: the overall direction of each line and which was highest.
  • →Group lines that move together instead of describing each one in turn.
  • →Give the start and end figures plus the peak or low point, not every value.
  • fluctuations

    irregular rising and falling in number or amount

  • threshold

    a point of entry or beginning of effect

  • neutrality

    the state of not being acidic or alkaline

  • dramatic

    sudden and striking in appearance or effect

  • gradual

    taking place or progressing slowly by degrees

  • conversely

    introducing a statement that reverses a previous one

Frequently asked questions

What should the overview say?+

All three substances cause a rapid increase in mouth acidity immediately after consumption, with cane sugar having the most prolonged effect on pH levels.

How many words and how long for IELTS Writing Task 1?+

At least 150 words; 170 to 200 is the safe range. Spend about 20 minutes on it and leave 40 for Task 2, which carries twice the marks.

How is IELTS Writing Task 1 scored?+

On four criteria: task achievement, coherence and cohesion, vocabulary, and grammatical range and accuracy. A clear overview of the main features is what most separates Band 6 from Band 7 and above.

How do I describe line graphs?+

Overview first: the overall direction of each line and which was highest. Group lines that move together instead of describing each one in turn. Give the start and end figures plus the peak or low point, not every value.

Keep practising

More line graphs

© 2026 BandLadder. Written and checked by the BandLadder team. You may quote or cite this page with credit to BandLadder and a link to it; republishing it in full needs our written permission. Content use policy

Write a report, get a band free