A child in Clementi finds a useful explanation of evaporation in an electronic textbook. On her tablet it is at page 84. She sends a message to a classmate: “Read page 84. That is the part our teacher wants.” The classmate opens the same edition on a phone. Page 84 contains a different paragraph—or there is no familiar page number at all. Nobody is necessarily using the wrong book. The words may be the same while the layout has changed.
Why do eBook page numbers change when you change font size or move from a tablet to a phone? In a reflowable digital book, text is laid out inside the available screen. A larger font, narrower screen, wider margins or different reading app can alter how many words fit on each displayed screen. That visible screen is not always a fixed printed page. Some books include an explicit map back to print pagination; others provide only locations, progress percentages, chapters or search. Readers need to distinguish a movable display boundary from a stable way to identify a passage.
This matters when students cite sources, parents help locate homework, teachers assign readings and classmates compare notes across devices. The issue is not that digital books are unreliable. Reflow is often an accessibility feature: it lets readers choose a comfortable text size instead of forcing everybody into one frozen page design. The task is to preserve the location of meaning even when the page’s shape changes.
The answer in 50 seconds
An eBook may use reflowable text: the words rearrange to fit screen size, font, spacing and orientation. As a result, a number shown as the current screen or location may change with those settings. Some eBooks are fixed layout, preserving page geometry; some reflowable editions include print page markers supplied by the publisher, and reading applications vary in how they display them. Do not assume every number labelled “page” means the same thing.
For dependable school reading, identify the book’s edition and use a chapter or section title, a short unique phrase, and a bookmark or highlight tied to the passage. If citing an eBook academically, follow the required style and cite stable locators such as chapter, section or paragraph when page mapping is unavailable. Teachers should give students a heading and a few identifying words alongside any page reference. Parents can help search for the exact sentence rather than insisting that two screens must have identical pagination.
The physical page and the digital screen are not the same unit
In a printed book, pages are part of a manufactured layout. A publisher chooses trim size, margins, typeface, line spacing and page breaks, then prints those choices on paper. A reference to page 84 identifies a physical location in that edition, subject to usual edition differences. In a reflowable eBook, the publication may provide structured content and styles while the reading system decides how to display the text on a particular screen. W3C’s EPUB 3.3 Recommendation, issued 13 January 2026, describes EPUB as structured web content packaged for distribution. The reading system is not simply photographing a printed object.
A phone in portrait orientation may display twelve lines of a paragraph. A tablet in landscape orientation may display thirty. Increasing the font for comfortable reading can put the paragraph on another screen. This changes the location of a screen boundary, not the underlying claim about evaporation. Once students see that difference, the puzzle becomes a navigation problem rather than a disagreement about which passage exists.
What reflow is doing behind the scenes
Think of a paragraph as a stream of words with structural boundaries: paragraphs, headings, emphasis, lists and links. In a reflowable presentation, the reading software measures an available display area, uses font metrics to lay words onto lines, then places those lines onto screens or virtual pages. Change the screen width and many lines break at different words. Change the font size and the number of lines fitting vertically changes too. A tiny adjustment early in the chapter can move later text to a different displayed screen.
This is not like a film frame cut into fixed stills. It resembles water taking the shape of a container while remaining the same substance. The analogy has limits: typography involves complex scripts, ligatures, images, footnotes, tables and page-break rules that cannot always be reflowed seamlessly. But it captures the essential reason two readers can see different page positions while reading the same semantic content.
Fixed-layout books solve a different problem
A fixed-layout eBook preserves much more of the geometry of a page. That can be valuable for picture books, comics, illustrated textbooks, art publications, notation-heavy scores and materials where the spatial relationship among items is part of the meaning. A chart labelled with arrows may be easier to preserve as a composition than to rearrange into a narrow phone column.
The cost is reduced flexibility. Enlarging the text may require zooming and panning. A narrow display may show only part of a page. A fixed layout is not automatically accessible simply because the page numbers remain stable, and a reflowable layout is not automatically accessible just because text resizes. Accessibility involves semantic structure, reading order, alternatives and navigation. Teachers assigning a visually complex page should check how it behaves in the actual reading apps their pupils use.
There may be three different numbers on the same screen
A reader might see a chapter number, an app-generated page or location number, and a print page number embedded by the publisher. These are different coordinate systems. Chapter 7 identifies content structure. A location number may reflect software’s internal measurement of position. A print page label may map the digital passage to a page boundary in a specific printed edition. A percentage complete describes a relative position in the reading experience, not a precise citation unit.
When a learner writes “page 84”, ask which of those numbers they mean. Did the number remain the same after changing text size? Does the app say “print page”? Does the book include an explicit page list? Is the number attached to an edition? Two students can each be accurate in their own coordinate system while their messages fail to identify one shared location. The repair is to include a stable textual landmark.
The first classroom test takes thirty seconds
Open the same passage in a permitted reading app. Write down the displayed page or location. Increase the font size one or two steps. Note whether the page number, amount of text visible and percentage position change. Next rotate the device if the app supports it. Compare the result. If the text reflows, the changes are direct evidence that the visible layout depends on the reading environment.
This demonstration teaches a precise lesson. It does not establish that every EPUB behaves this way; a fixed-layout edition may stay visually stable. It also does not prove that the app’s internal location markers are unreliable; an app can offer multiple navigation systems. The result is about the particular edition and reading system being used. That is exactly the habit we want students to develop: test a claimed property under its actual conditions, not by guessing from the file extension.
A five-part locator survives more change
For important learning passages, use a locator with five optional parts: the work title, edition or publication date, chapter or section title, a short distinctive phrase, and a bookmark or hyperlink when available. All five are not required every time. For quick homework instructions, “Chapter 4, Water Cycle, paragraph beginning ‘When warm air rises…’” may be plenty. For research citations, edition identity and formal citation rules become more important.
Why does this work? A chapter heading stays attached to the content even when it moves to another screen. A distinctive phrase can be searched when the reader app indexes the text. An edition label prevents the class from comparing a revised textbook with an older one without realising it. A bookmark may provide a direct jump within one account or device, though syncing and shareability vary. The locator targets meaning, not a momentary screen position.
The search box is helpful but not infallible
Searching for an exact phrase can locate a passage quickly. Yet search has limits. A learner may be using a scan without a reliable text layer. An equation might contain specialised mathematical symbols that the app tokenises differently. Punctuation, line breaks, language-specific spelling, hyphens and accents may affect a search. A phrase can occur several times, such as “the experiment shows”, making it a poor locator.
Choose the smallest unusual phrase that still belongs to the intended passage. If search fails, browse from the chapter heading or use the table of contents. The companion issue of why a visible word can remain unsearchable in a scanned PDF is a separate technical mechanism: this article concerns location stability after reflow, not optical character recognition. Keep the two diagnoses distinct before changing the reading app or blaming the file.
An edition mismatch can look like a page mismatch
Suppose two children each own an electronic copy titled Introduction to Ecosystems. One is a revised 2026 school edition; the other is an earlier edition downloaded from an old folder. The page differences might come from changed content, not reflow. A sentence may have been rewritten, a figure moved, or an example replaced. In that case even searching the same phrase might fail for a legitimate reason: the text is not identical.
Before diagnosing a display problem, compare title, publisher, publication year, edition and chapter heading. Teachers should share the permitted edition identifier when assigning a reading. Students should avoid treating a cover image as proof that files are identical. Version mismatches matter most when a syllabus or worked example has changed; a locator is only as good as the identity of the document it names.
Homework instructions should have a fallback locator
Imagine a school message: “Read page 43 and answer the questions.” For paper books of the same edition, that may be sufficient. For a mixed-device digital class, it may strand learners who cannot map the number. A slightly more robust instruction would be: “In Chapter 3, read the subsection ‘Changes of State’, beginning with the paragraph about heating ice; in the printed edition this begins on page 43.” The extra words protect the task across more reading conditions.
Not every assignment needs a complicated reference specification. Use a stronger locator when confusion has actually occurred, when several file formats are in use, or when a misplaced section could derail the next lesson. Keep the student-facing instruction concise; if the locator takes longer to decode than the reading, it defeats its purpose. The goal is practical redundancy, not bureaucratic ceremony.
W3C page lists and why they matter
EPUB provides a way for publishers to include navigation such as a table of contents and a page list. The W3C EPUB Reading Systems 3.3 specification describes requirements to provide access to navigation links and encourages access to page breaks when page-list navigation exists. That creates a bridge between content structure and familiar page references, but the bridge must actually be present and supported in the edition and reading system.
A teacher should not claim that every eBook includes a print-page map. Nor should a student assume that a PDF and an EPUB from the same publisher share pagination. The page list is metadata-like navigation supplied by a publishing workflow; it is not created automatically from any screen layout. When a reading application shows print page numbers, look for documentation explaining what edition those numbers refer to.
Accessibility is part of the reason reflow exists
For some readers, larger text, different spacing or a narrower line can make reading more comfortable. Others benefit from alternative presentation, screen-reader navigation or language support. Reflowable content can respond to these preferences without requiring the reader to view a tiny, fixed page. A school that solves pagination disagreement by mandating one tiny font or forbidding text enlargement may trade a navigation inconvenience for an accessibility barrier.
The better solution is to decouple assignment locations from visual page shapes. Headings, semantic navigation and stable links allow teachers to communicate precisely while learners control presentation. W3C’s EPUB Accessibility 1.1 addresses digital publication accessibility beyond pagination, including discoverability and content requirements. A parent should not have to choose between helping a child find the assigned passage and letting that child read comfortably.
How a bookmark differs from a screen capture
A bookmark points to some representation of a reading position. A screenshot records a visual arrangement at one moment. The screenshot may help a classmate recognise a heading, but it is a weak universal locator when a different font, screen or edition rearranges the page. A screenshot can also omit the paragraph above that supplies a definition or exception, making the visible fragment misleading.
When sharing is allowed, a structured chapter link or quotation-sized phrase can be more usable than a full-page picture. Do not share copyrighted textbook pages publicly or upload an entire book without permission. For a small classroom clarification, use the institution’s approved sharing channel and follow its licensing rules. Navigation should help students find material they are entitled to use, not become an excuse to reproduce restricted content.
Parent route: help the child recover the location
Ask the child to show the message and the book’s title. Verify whether it is the right edition. Find the chapter in the contents, not by turning virtual pages at random. Then search for the section title or distinctive phrase. Once found, make a permitted bookmark and write one sentence in the child’s notes describing the passage. Ask the child to explain what they found, so the parent has not simply completed the navigation while the learning remains untouched.
If the same mismatch keeps occurring, send the teacher a specific query: “Our reflowable version does not match printed page 84. Could you identify the section heading?” That supplies evidence without assuming teacher error. A teacher may not know that the application uses dynamic page numbers. A clear report can improve future instructions for everyone while respecting the teacher’s workload.
Student route: create a small citation habit
Whenever a useful eBook passage will matter later, record more than the displayed page. Write the chapter, heading, one phrase and one idea in your own words. If the material supports an argument, note whether you are quoting, paraphrasing or making an inference. This creates a source trail and a learning cue simultaneously. Later, when the layout changes, the heading and phrase get you back to the evidence.
A practical test is to lend the locator—not the licensed book—to a classmate with a different device. Can they find the same passage in under a minute? If not, improve the locator. The test gives a visible criterion for useful note-making. It also teaches a wider research habit: cite sources in a way another reader can inspect, rather than relying on private memory of where a sentence once appeared.
Teacher route: design a reading instruction that travels
The most helpful intervention is often a five-minute test before setting the homework. Open the assigned book on a school laptop and, if permitted, one smaller device. Ask whether a chapter heading appears consistently and whether a key paragraph can be found using search. Do not assume that all families have the same reader, that the school’s digital licence works outside school, or that every child can make and export highlights. Teachers can put a stable textual locator in the learning management system even if the book itself cannot be shared.
For example, an instruction might read: “In Science Unit 4, open the section Heat and changes of state. Read from the paragraph beginning ‘When a solid gains energy’ to the diagram headed ‘Evaporation and boiling’. Write two differences, then explain which process occurs at the surface.” The locator names the relevant conceptual span rather than a device-dependent slice. A pupil who reads at double text size can still work on the same assignment. A teacher can check what counts as completion because the expected reasoning is explicit.
Sometimes the teacher must use page numbers because a school or examination system specifies a print textbook. Keep that number, but pair it with a second coordinate: page 84 in the school-issued printed edition, Section 3.2, first paragraph under a named heading. A dual locator is particularly valuable for a mixed paper-and-digital class. It also reduces the chance that a child spends the first fifteen minutes of study arguing with an app instead of examining the Science.
In a classroom, demonstrate the mechanism rather than merely telling pupils to be careful. Display the same text on two screens, enlarge one font, and invite a student to predict what will change. Ask them to recover one passage using only a page number, then using a section title plus a phrase. This is a small literacy lesson about documents as structures. It gives students a reason to record useful metadata and not just copy the most convenient number on screen.
The three-device test: a worked example
Consider a fictional assignment from a Clementi Primary 5 class. The teacher asks pupils to read an explanation of condensation from a digital Science resource. A child opens it on a school laptop with a 13-inch display, another on a tablet with enlarged text, and a third on a phone borrowed for a few minutes with the family’s permission. The laptop reader says “Page 42 of 106”; the tablet says “Page 58 of 151”; the phone uses “Location 1850” and a progress bar.
Do not interpret those figures as measurements from a real publisher; they are hypothetical representations to show how interfaces can differ. The correct comparison is content, not the number itself. All three children search for the section heading “Condensation” and locate a paragraph beginning with the same six words. They read it aloud and check the explanation against the accompanying diagram. Once their common passage is established, it is perfectly acceptable that the progress numbers differ.
Now the teacher asks for an answer: “Why might water droplets form on the outside of a cold cup?” One child writes that the cup has leaked. Another says vapour in the surrounding air loses energy and condenses on the outer surface. The teacher can now address the conceptual difference. Had the class stayed at the pagination dispute, the actual Science misconception would never have appeared. A robust locator is not a paperwork trick; it protects the time needed for learning.
The test also reveals an important edge case. If one child sees a different diagram caption or a paragraph that contradicts the others, the group may be using different editions rather than merely different layouts. Search for the edition statement, copyright date and resource version. Do not blame reflow for a genuine text revision. The distinction matters when a syllabus or safety instruction has changed.
Page numbers, references and honest academic citations
There is a difference between finding a passage for homework and making a formal citation in an essay. For homework, the chapter and identifying phrase may be enough to get another reader to the right place. For a formal assignment, students should follow the citation style required by the school or institution. Some styles provide instructions for sources without stable page numbers, such as using section names, chapter divisions or paragraph identifiers. Students should not invent a page number by counting screens or claim that an internal reading-app location corresponds to print page 84 unless that relationship has been verified.
An academic citation must identify the source as well as the position: author or organisation where appropriate, title, edition or version, publication details and a locator that helps the reader retrieve the claim. The citation can also include a DOI or stable URL when the source provides one and the assignment calls for it. A bookmark useful to one student’s app may disappear when the subscription expires or the reader changes; that makes it a poor sole academic locator.
Quote with care. A few distinctive words can help locate a passage, but a student must still read surrounding context to interpret it. Searching for a sentence and copying it into an answer may skip the argument that gives that sentence its meaning. If a textbook says “This rule holds when the system is closed,” deleting the condition makes a broader claim than the source supports. Good source tracing therefore combines mechanical retrieval with comprehension. The machine finds text; the student judges the claim.
When the book is a PDF rather than an EPUB
A PDF often preserves a fixed page-like presentation. If two readers open the same PDF file and view its numbered pages, the boundaries typically remain stable even when zoom changes. But a printed page number within the artwork may not equal the PDF viewer’s page index. A document can contain a cover, acknowledgements and roman-numeral front matter before numbered Chapter 1 begins. A viewer may say “PDF page 19” while the scanned page itself is printed “Page 7.” Neither label is necessarily an error.
Teachers should specify which coordinate they mean when a mismatch is likely: “Printed page 7, the page with the heading ‘Fractions as operators’,” rather than the ambiguous “PDF page 7.” Students can use thumbnail previews and text search to confirm the location. A file may also contain inserted appendices or a revised cover, shifting the numerical offset while leaving its educational content intact.
The PDF distinction becomes especially important when text is scanned as an image. The visual page may remain beautifully fixed, but text search may fail because the document contains no searchable text layer. That is a separate mechanism from reflow and needs its own troubleshooting. For image-capture quality, the site already covers why homework photos can be difficult to read. Here the canonical question remains the location of a passage across different digital layouts.
What happens to tables, mathematical symbols and diagrams?
A reflowable book may handle an ordinary paragraph elegantly and struggle with a two-column equation derivation or a labelled diagram. Some reading systems keep complex objects at a fixed width; others let the reader zoom or display them separately. A long mathematical expression can wrap poorly or extend beyond the visible area. A child who cannot see the exponent may make a genuine mathematical mistake that began as a presentation problem.
The remedy is not to assume that reflow preserves every relationship automatically. When assigning a notation-heavy excerpt, the teacher can test the actual reading experience, provide an accessible alternative for a specific figure where licensing permits, or direct the child to a correctly rendered resource supplied by the publisher. The student can use the authorised zoom or alternative display rather than manually reconstructing a complicated equation from a truncated screenshot.
For Science, remember that spatial relationships may carry meaning. A water-cycle diagram uses arrows to represent a sequence or movement, not merely to decorate the paragraph. If an app places the explanation far from its figure, the student may need to navigate between them. A stable textual locator should name the figure or caption as well as the chapter. Good reading guidance respects both the semantic structure and the visual parts that help the learner understand it.
The seven most common failed fixes
Fix one: force everyone to use the same font size. This may make a screenshot comparison easier for a few pupils but can block readers who need larger print. The task needs a robust locator, not identical eyesight or devices. Text customisation is part of the benefit of reflow.
Fix two: assume the screen count equals print pagination. A counter generated by one reading app may reflect that application’s layout choices. Confirm whether the publisher supplied a print page map before using its numbers in a formal citation.
Fix three: blame the pupil for using the wrong edition before checking. Edition differences certainly occur, but layout differences can occur even with identical content. Compare a heading and sentence first. Escalate to edition or file-version checks only when the content itself diverges.
Fix four: share a screenshot as the only location instruction. A screenshot can hide surrounding context, be hard for screen-reader users and accidentally expose account details or class information. Pair permitted images with text headings and locators when visual clarification is useful.
Fix five: copy a location number from a proprietary app into every student’s homework. A location number may be meaningful only within that application or file version. It is a convenient personal bookmark, not a universal address.
Fix six: switch entirely to a PDF to avoid reflow. Fixed pages do solve some layout coordination problems, but may create accessibility and navigation trade-offs. Choose formats according to learners and material, and give cross-format references.
Fix seven: stop at finding the correct page. A child can navigate perfectly and misunderstand the concept. The real educational success condition is the child’s explanation, worked solution or question about the content, not a matching numeral in a page counter.
A family troubleshooting sequence that fits in five minutes
Begin with the assignment, not the app’s settings menu. Read the teacher’s instruction verbatim. Is the requirement a page range, a section, a named activity or a particular figure? Open the table of contents. Search for a heading or distinctive phrase. Confirm one sentence of the content, then return to the actual task. Do not spend ten minutes fine-tuning fonts in the hope that another family’s screen geometry will appear.
If the school specifies a printed edition and your digital resource is different, record the edition information and use the assigned chapter and heading. If a link does not open because the account lacks access, report the access problem to the school rather than trying to evade licensing. If the heading itself is absent, ask whether the student has been issued the correct book or whether the resource has been updated. A clear screenshot of the app’s bibliographic information may help support staff, provided personal data are removed or appropriately shared.
End by asking the child to explain what the passage says in one sentence. This checks that the navigation work actually led to reading. If the child has merely landed on a familiar keyword but does not understand it, the next move is instruction, not more technical troubleshooting. The difference between finding information and learning it is worth making explicit.
What a school can standardise without standardising everybody’s screen
Schools can adopt a light convention: every digital reading assignment gives the resource title, edition or version when material, unit or chapter, named section, and the beginning or ending phrase if the section is long. Where students use a common learning management system, a deep link or internal resource identifier can supplement the human-readable location. The convention should be simple enough to survive teachers’ busy weeks.
Publishers and platform administrators can help by preserving document structure and page-list navigation when supported. Accessibility staff can test whether screen readers announce headings and whether navigation survives larger text. Teachers can report systematic confusion instead of treating each student’s message as an isolated complaint. These are modest design choices that reduce repeated friction for entire cohorts.
There is a caution: a direct link can break when the licensing system, resource version or school account changes. A human-readable description is a recovery route if the link fails. Conversely, a title and heading may not be enough if a publisher has five sections named “Introduction.” Use two independent locators where the cost of landing in the wrong place is high. Redundancy is useful when it is intentional and small.
Frequently asked questions
Why does my eBook say page 84 on an iPad but page 107 on a phone?
If both devices are showing the same reflowable edition, the screen or page count may be generated from how the text fits each display. Font size, margins and orientation change the layout. Compare the chapter heading and a unique phrase; then check whether the app is showing a dynamic page count or actual print page markers. If the wording differs, investigate the edition and file version rather than assuming layout alone explains it.
Does changing font size change the book itself?
Usually it changes the presentation, not the underlying words, in a properly functioning reflowable book. Some complex layouts may move images or change how equations are displayed. If the child notices omitted content, a broken table or text disappearing outside the screen, do not dismiss it as a harmless pagination difference. Report the rendering issue and provide an accessible authorised alternative where available.
Are Kindle locations the same as EPUB page numbers?
No universal equivalence should be assumed. A reading application may provide internal location units, percentage progress or a mapping to a printed edition. The way an individual product labels those positions may vary by app and format. For school assignments, a chapter and textual anchor are more portable than a proprietary location number. If a formal citation style requires a specific locator, consult the relevant official guidance.
Can I cite a page number shown on my screen?
Only with care. If the screen clearly displays publisher-supplied print page mapping linked to a specified edition, it may support a conventional page citation. A dynamically generated virtual page is not necessarily a stable reference for other readers. Record enough source information for a reader to retrieve the passage and use chapter, section or paragraph locators if the required citation style allows them.
Why does my PDF reader say page 19 when the textbook says page 7?
The PDF viewer may count the cover, contents and other preliminary pages, while the printed page number starts later. Find the numbered page visible within the document and compare a section title. When assigning a PDF range, specify whether you mean the viewer’s page index or the number printed on the page; use a heading as a second check.
Does a screenshot solve the page mismatch?
It can help identify a familiar figure but is a weak sole locator. The screenshot is tied to one screen arrangement and may omit context. It can also be inaccessible to some users or breach a content licence when distributed widely. Prefer a heading, a short permitted identifying quotation and the resource’s authorised navigation features.
How should teachers assign the same chapter to a mixed-device class?
Name the edition where relevant, then give the chapter, heading and the start or end of the required passage. Add a print page reference as an aid, not the only identifier. Test a phone and laptop view if possible, especially for complicated diagrams. Define the learning task so pupils know what they should be able to explain or do after reading, not merely where to stop scrolling.
What if search returns no result for a phrase I can clearly see?
First verify spelling, punctuation and whether the text is an image rather than selectable text. Try searching a shorter distinctive term or a heading. Some scanned PDFs contain only pictures of pages until optical character recognition creates a searchable text layer. A different article should own the details of that text-layer problem; for this question, manual heading navigation and edition verification remain sensible short-term routes.
Why does this matter beyond homework?
Digital reading appears in workplace manuals, scientific papers, library books and public information. A professional instruction that relies on “the third screen after the blue paragraph” is as fragile as a school instruction that relies on one app’s page count. Learning to cite an edition, heading and inspectable passage teaches a transferable form of information literacy: the ability to recover evidence after the interface changes.
Evidence, limits and sources
This article explains a document and publishing mechanism, not a claim that one reading format guarantees stronger attainment. The W3C EPUB 3.3 Recommendation, dated 13 January 2026, defines the publication format; the EPUB Reading Systems 3.3 Recommendation addresses how reading systems support its features, including navigation; and EPUB Accessibility 1.1 provides requirements for accessible publications. These are authoritative technical standards rather than controlled studies of Singapore classroom learning gains.
- W3C, EPUB 3.3.
- W3C, EPUB Reading Systems 3.3.
- W3C, EPUB Accessibility 1.1.
- CAST, Universal Design for Learning Guidelines, representation and meaning.
For adjacent mechanisms, see eduKateSG’s existing eBook localisation, reflow and accessibility explainer and first principles of education. This article owns a smaller, practical question: how a pupil and teacher recover the same passage when page numbers move across devices. A page number is one possible address. The meaning you have to study must remain findable when the address changes.