Thesis Defense Presentation: Structure, Slides, Timing

A good thesis defense presentation answers three questions in a few minutes: what was your topic, what did you find, and why does it hold up? How long your talk may be is set by your university, usually somewhere between 15 and 30 minutes. There is no single figure that applies everywhere.

What is the presentation in a thesis defense, and what is it not?

The colloquium is the oral exam on your bachelor's or master's thesis. At many universities it begins with a talk followed by an examination conversation. The presentation is therefore only one half; for the other half, the examiners' questions, we have a separate article: Thesis defense: typical questions and how to answer them. This article is about the talk itself: structure, slides, time.

The difference from submitting your thesis matters: your written work has already been graded or is being graded in parallel. In the talk you do not have to prove that you wrote everything down, but that you can explain it. TU Braunschweig gives an example in its notes for bachelor presentations in biology education: it is the presentation that is assessed, and there is "no second assessment of the BA thesis" (our translation).

How long is the defense, and how long is the talk?

It varies a lot by university. Four examples from real documents, expressly examples only:

• University of Göttingen (older examination regulations, 2003–2011 version, Agricultural Sciences, master's): the colloquium consists of an oral presentation of 20 to 30 minutes and a subsequent discussion, at most 60 minutes in total.
• TU Braunschweig (notes for biology/biology education, bachelor's, dated 2017): a short talk of 15 to 20 minutes, followed by an assessment conversation.
• Frankfurt University of Applied Sciences, Faculty 1 (information sheet, dated 2023): the colloquium lasts at least 30 and at most 45 minutes and should take place no later than six weeks after submission. The sheet does not say how much of that is the talk.
• University of Trier (social and organisational education, bachelor's): a colloquium of 30 minutes in total, including the announcement of the grade. The concept paper prescribes no presentation; instead the first examiner formulates questions from reading the thesis at least a week beforehand, and you may bring in theses of your own.

The range shows the point: if you prepare 20 minutes where only 10 are asked for, you have a problem, and if you plan a slide marathon in a Trier-style format, you are preparing for the wrong thing. Before you build a single slide, read the examination regulations and information sheet for your programme and, if in doubt, ask your supervisor: duration, whether a talk is required, permitted aids, language, what happens if you overrun.

How do I structure the presentation?

A proven structure follows the path of your thesis, shortened and sharpened. The Braunschweig notes list, among other things, the relevance of the topic, the aim of the work, the factual content, and, if applicable, a summary and outlook. From that you can derive this outline (the time shares are a rule of thumb of this article, not a requirement of any regulation):

1. Opening and topic (about 10%): What is it about, and why does it matter? A concrete example or a question works better than "Outline" as the first slide.
2. Research question or aim (about 10%): One or two sentences. If the audience does not know what you investigated after this slide, everything else is wasted.
3. Approach and method (about 20%): What did you do, and why that way? Only what is needed to understand the results.
4. Results (about 35 to 40%): The core. Show the most important findings, not all of them.
5. Discussion and limits (about 10 to 15%): What do the results mean, and what can your work not do? Naming the limits yourself often takes the wind out of examiners' sails.
6. Conclusion and outlook (about 5 to 10%): The answer to the research question in one sentence, then a look ahead.

A clear common thread helps more than any design idea: the Braunschweig notes also ask for an outline the audience can follow and a common thread through the whole presentation.

How many slides do I need, and what should they look like?

Few regulations prescribe a fixed number of slides. As a rough rule of thumb (also not from any of the sources named here), you can count on about one to two minutes per slide: for 15 minutes that would be roughly 8 to 12 slides. More important than the number is that each slide carries exactly one message.

Concrete design advice from the Braunschweig notes that transfers easily:

• Font size at least 18 points. It looks very large at first, the notes say, but is essential for the audience sitting further back and helps you avoid putting too much on a slide.
• No fully written-out sentences, except for quotations and definitions.
• Sources belong on the slide, with credits for figures on separate slides at the end.
• Figures and tables in a reasonable size, otherwise nobody can see them from the back.
• High contrast: there, the presentation is even requested as a black-and-white handout with six slides per page, so the background should not be dark. Whether that applies to you is stated in your own documents. As a principle it still works: slides that stay legible in a black-and-white printout stay legible on any projector.

And one rule from experience: keep a reserve. Anything that is not needed for understanding but could help with a follow-up question belongs on a backup slide after your closing slide, not in the talk.

How do I keep to the time?

The time limit is not a suggestion. Braunschweig states explicitly that a considerable overrun leads to a worse grade. Three habits help:

1. Practise out loud with a stopwatch. Running through it in your head always takes less time than speaking. Plan two or three full run-throughs.
2. Set time markers. Note which slide you should be on at the halfway point. That way you notice early whether you need to catch up.
3. Leave some buffer. Plan two to three minutes under the limit. Nerves change your pace, and technology sometimes needs a few seconds.

The Braunschweig notes also recommend a rehearsal in front of friends or a mirror, followed by revision, and speaking freely without a read-out script. A keyword card is often enough; memorising whole sentences is not: if you lose the thread once, keywords help you find it again faster.

What do I do on the day itself?

• Check the technology: does your file run on the computer in the room? The Braunschweig notes explicitly ask you to check compatibility with the presentation laptop. A PDF copy on a USB stick is a sensible backup.
• Stand and speak up: the notes say talks are given standing, which creates more attention and supports the voice.
• Look at the audience, not the screen. The slide is scenery, not a script.
• Listen after the talk: questions are not an attack but the second part of the defense. Taking notes and thinking for a moment looks confident.

How do I practise without an audience?

A real counterpart works best: fellow students, flatmates, your supervisor if there is time. If nobody is available, record yourself on your phone and listen back. For the part that follows, the examination conversation, an oral exam simulation can help by asking questions about your own materials. What such questions look like is covered in the article on typical thesis defense questions.

Conclusion

Read your university's requirements first, then build a short common thread from question through method and results to conclusion, keep the slides legible, and practise with a stopwatch. More material for the weeks before your exam is in the exam preparation category. LearnCastAI can support your practice with summaries and questions on your own materials; the talk itself you still have to give, and that is as it should be.