Using Prepositions Correctly to Specify Time in the English Language

Using Prepositions Correctly to Specify Time

Prepositions are small but powerful words. They signal relationships—often spatial or temporal—between elements in a sentence. In academic writing, prepositions of time are particularly important because they help readers understand when something happened, how long it lasted and how different events or stages in a project are related. A poorly chosen preposition can change the intended meaning of a timeline, blur the description of a method or create confusion about a deadline.

Grammatically, a preposition combines with a noun, pronoun or noun phrase known as its complement or object. Together they form a prepositional phrase, such as in 2023, at noon or during the experiment. These phrases act like adverbs or adjectives: they modify verbs (data were collected in May), adjectives (stable over time) or even other adverbs (performed well during exams).

Unlike verbs and nouns, prepositions are non-inflected: their forms do not change with tense, number or person. The difficulty lies not in conjugating them but in choosing the correct one and placing it naturally in the sentence. This is especially challenging for authors whose first language uses different prepositions or structures to express time. The good news is that English follows fairly stable patterns, and once you internalise them, using prepositions of time becomes much easier.

1. Prepositions and Word Order: Stranded or Not?

As the name suggests, a preposition is typically placed before its complement. In formal prose, this is still the preferred pattern:

• “Data collection began in January 2022.”
• “The interviews were conducted during the spring semester.”

In everyday speech and in questions, however, English frequently allows stranded prepositions, where the preposition appears at the end of the clause rather than before its object:

• “Which month did the study start in?”
• “That was the semester we collected data during.”

In highly formal scholarly prose, some writers prefer to avoid stranding and instead use structures such as:

• “In which month did the study start?”
• “During which semester were the data collected?”

However, attitudes are changing, and many editors accept stranded prepositions where the alternative would sound stilted. The key is consistency and tone: in research articles and theses, aim for the more formal pattern, while recognising that an occasional stranded preposition—especially in a research question or informally phrased example—is no longer regarded as a serious fault.

2. Points in Time: At, In and On

One of the most frequent tasks in research writing is to anchor events to specific points in time. English uses the prepositions at, in and on to do this, each with its own typical “time scale.” Choosing correctly is largely a matter of matching your time expression to the right preposition.

2.1 At – Exact Times and Fixed Points

Use at for clock times and certain fixed moments:

• “The experiment started at 8 a.m.”
• “The online survey closed at midnight.”
• “Participants arrived at three o’clock.”

Certain words for parts of the day also take at:

• “She usually writes at night.”
• “The birds became active at dawn.”
• “We met at noon for a progress discussion.”

Think of at as pointing to a precise “dot” on the timeline—an exact time or a conventional point such as midnight or dawn.

2.2 In – Months, Seasons, Years and Longer Periods

The preposition in is used for larger blocks of time, such as parts of the day, months, seasons and years:

• “She prefers to analyse data in the morning.”
• “They usually write in the afternoon.”
• “There is usually heavy rainfall in January.”
• “Fieldwork takes place in the summer.”
• “The first article was published in 1998.”

Here, in suggests being located inside a period of time rather than at a precise instant. A useful guideline is that if the time unit is relatively long or fuzzy, in is often correct.

2.3 On – Days and Specific Dates

Use on with days and dates:

• “The lecture is on Monday.”
• “I visit the library on Saturday, but he usually goes on Sunday.”
• “The conference opens on 23 February.”
• “Ethical approval was granted on 14 March 2023.”

In some varieties of English, especially in speech, you may hear dates expressed without a preposition (“The conference opens 23 February”). For formal academic writing, however, using on before a day or full date is usually clearer and more standard.

2.4 A Simple Visual Aid

Many learners find it helpful to imagine a timeline with different levels of zoom:

• at = exact point (08:00, noon, midnight)
• on = one whole day or specific date
• in = longer period (month, season, year, decade)

If your time expression refers to a point, choose at; if it refers to a day, choose on; if it refers to a larger container of time, choose in.

3. Extended Time: Between, By, During, For, Since, Within and From … To

Academic texts rarely mention single time points in isolation. More often, you need to describe periods and durations: when a study started and ended, how long an intervention lasted, how long participants were observed and when a deadline applies. English uses a range of prepositions for this purpose. Each emphasises a slightly different aspect of the time relationship.

3.1 Between – From One Limit to Another

Use between to specify a stretch of time with clearly defined start and end points:

• “The show was playing in town between Christmas and Easter.”
• “Data were collected between March and May 2022.”

Between focuses on the space separating two points. It does not, by itself, indicate whether the endpoints are included, so if that matters, clarify it elsewhere (for example, by giving precise dates).

3.2 By – No Later Than a Certain Time

The preposition by is crucial for deadlines. It means “no later than”:

• “The manuscript must be submitted by 30 June.”
• “It has to be finished by tomorrow.”

In these sentences, the task can be completed earlier, but not after the stated time. When communicating deadlines to students or collaborators, by is often clearer than alternatives such as until, which can be misinterpreted.

3.3 During – At Some Point Within a Period

Use during when something happens at one or more unspecified times within a larger timeframe:

• “He watches soap operas during the day.”
• “Several unexpected events occurred during the fieldwork phase.”

During tells us when in a broad sense but not how long. For explicit duration, you will usually need for.

3.4 For – Duration or Length of Time

The preposition for expresses how long something lasts:

• “I am on vacation for two whole months.”
• “The participants were observed for six weeks.”
• “The intervention continued for three sessions.”

Note that in many languages, the equivalent of for can be omitted, but in English it is usually required to avoid ambiguity.

3.5 Since – From a Point in the Past Until Now

Use since to indicate that something began at a specific time in the past and continues up to the present (or up to a specified point in reported time):

• “She has been missing since last week.”
• “The pattern has remained stable since 2010.”

Since is typically used with the present perfect or past perfect, not with simple past. It emphasises continuity from the starting point to “now.”

3.6 Within and In – Deadlines Inside a Period

Within indicates that something must happen at some time before the end of a given period, with a slight emphasis on the boundary:

• “The research has to be finished within a month.”

In many contexts, you can also say:

• “The research has to be finished in a month.”

Both sentences suggest a deadline approximately one month from now, but within highlights that any time before the end of that month is acceptable. In formal instructions or ethics documents, within often sounds more precise.

3.7 From … To / Until – Explicit Start and End Points

Finally, the preposition from is commonly used with to or until to express periods with clear boundaries:

• “The study focused on events that occurred from the beginning of 2011 to the end of 2013.”
• “Our Christmas tree was up from 1 December until 31 December.”

It is better to avoid using from without a corresponding to or until in formal writing: “from 2011” alone feels incomplete. Instead, use since if you mean “from 2011 until now,” or complete the phrase (from 2011 to 2013).

4. Common Problems and How to Avoid Them

Even experienced scholars occasionally struggle with prepositions of time. Here are some recurring issues and ways to resolve them.

4.1 Confusing by and until

By sets a deadline; until emphasises continuity up to a point. Compare:

• “Submit the assignment by Friday.” (Any time before or on Friday is acceptable.)
• “Work on the project until Friday.” (Continue working and stop on Friday.)

For clarity in instructions and ethics documentation, choose carefully between these two.

4.2 Overusing during Where for Is Needed

Authors sometimes write sentences such as:

• “Participants were observed during six weeks.”

This sounds unnatural in English. Because you are specifying a duration (six weeks), for is required:

• “Participants were observed for six weeks.”

Reserve during for more general periods (during the semester, during the experiment) rather than exact lengths of time.

4.3 Interference from Other Languages

Many languages use the equivalent of in or on more widely than English. As a result, authors may produce phrases such as “on January” or “in Monday”. Remember the English pattern:

• in + month / season / year (in May, in winter, in 2022)
• on + day / date (on Monday, on 23 May)
• at + clock time / fixed point (at 9 a.m., at noon)

5. Practical Tips for Revising Prepositions of Time

Because prepositions are short and easily overlooked, it helps to develop a systematic approach when proofreading your own work:

• Highlight time expressions. As you revise, quickly underline or highlight every mention of a time, date, year or duration. Then check whether the preposition fits the pattern described above.
• Read methods and timelines aloud. When you say the sentences aloud, unnatural combinations such as during six weeks or on January often sound wrong, even if you did not notice them on the screen.
• Compare with model articles. Look at how high-quality journals in your field express similar timelines. You will quickly see recurring phrases such as in 2019, during the study period, for 12 months and from 2017 to 2020.
• Create a mini-reference sheet. Keep a short list of common time expressions and prepositions on your desk (for example: at + time, on + day, in + month/year, for + duration, since + starting point). Refer to it while drafting until the patterns become automatic.

Conclusion

Prepositions of time are among the most frequently used—and frequently misused—elements in English academic writing. Because they are so small, it is easy to overlook them, yet they carry crucial information about when research was conducted, how long processes lasted and how different stages relate to each other. Mastering the basic patterns with at, in, on, between, by, during, for, since, within and from … to will allow you to describe time relationships with clarity and confidence.

By paying attention to these patterns as you draft and revise, and by comparing your usage with that found in well-edited journals, you can gradually eliminate awkward or ambiguous prepositional choices. The result will be prose that not only communicates your findings accurately but also meets the high standards of precision and readability that characterise successful scholarly writing.