Academic Writing Task 1 · line graph

The impact of different sugars on mouth acidity and tooth decay

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)

Fruit sugar
Cane sugar
Honey

View the data

	Moment eaten	5 minutes	10 minutes	15 minutes	20 minutes	25 minutes	30 minutes	35 minutes	40 minutes
Fruit sugar	7	4.2	4.9	5.2	5.5	6	6.8	7	7.1
Cane sugar	7	3.6	3.9	4.5	4.6	4.9	5.3	6.2	7.1
Honey	7	4.8	4.8	5.6	6.6	7	7.1	7.1	7.1

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.

Band 8 sample answer

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.

180 words. Every figure in the answer comes from the chart above.

How to write about 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.

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

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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 long should an IELTS Task 1 answer be?

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 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.