Scientific Communication CITS7200

Lecture 10Giving a Talk

• Good presentation skills are vital in many professions and contexts

• Research seminars, conference talks, project meetings, budget meetings, sales talks, funding applications, job interviews, meeting your future in-laws, …

Key points

• Know your audience– What do they know?

What do they want to know?

• Figure out what they will learn and why they want to learn it

• Be professional– Organise yourself, your materials,

and your time

What to say and how to say it

• A good talk can usually be split into five parts

1. Definition and motivation of the problem

2. General theory3. Details4. Conclusions5. Question time

Define and motivate the problem

Defineand motivatethe problem!

Define and motivate the problem

• First impressions count!• Be concrete, not abstract

– Be concrete in motivation and in details– Generalise in conclusions, if appropriate

• Motivate with applications, philosophy, history, predictions, dollars, …

• Cover background only where necessary for understanding or for motivation

• Set up the notation and terminology– Keep notation (especially) to a minimum– Keep examples as simple as possible

• Remind, but do not assume• Emphasise your contributions• Often a “road map” to the talk

helps to impose structure

The general theory

• Describe the methodology• Describe the key results• Explain the significance of the

results• Sketch the proof/evidence of the

results– Pictures/graphs help

The details• Present one key result which is

– Important– Non-trivial– Representative

• Now give details– But this is the part of the talk that is

least important, and should be first to be cut

– Refer them to the paper/notes, if necessary, or to later discussion

The conclusion

• Put your results back in context– Once again, motivate the problem– Make clear your contribution

• Discuss any limitations• Discuss some interesting open

problems• Conclude: thank the audience, and

invite questions and comments

Handling questions

• Always allow time for questions– There are always questions!

• Allow/encourage questions during the talk, if you are confident enough

• Try to anticipate likely questions• Try to learn from the questions

Visual and aural aids

• High tech– PowerPoint, LaTeX, HTML, PDF, others

• Medium tech– Overheads, slides

• Low tech– Pen and plastic, whiteboard

General points

• Use large font sizes• Write points, not sentences• Do not put too much on one “slide”• Make the medium invisible

High tech

• Use presentation software if possible– Forces you to prepare in advance– Helps you to organise your talk– Makes changing your talk easier– Looks professional and well-prepared

• But plan for equipment failure, or portability issues– Have a lower-tech back-up plan

Medium tech• Overheads are good as a

back-up mechanism• But printed overheads can look

boring– And a mixture can look odd

• Always use permanent pens• With slides, video or audio:

be in control of the situation yourself, and prepare

Low tech

• Recommended only for confident speakers

• Allow you to tune the presentation on-the-fly

• Allow you to build up complex pictures/equations/graphs on-the-fly in any order, and to control the audience’s attention

Pointers

• Stick pointers are easier to aim– But don’t bang on non-rigid screens!

• Laser pointers give you more range– But avoid these if your hands shake

Voice issues• Face the audience, not the projector

screen, nor the computer screen, nor the OHP, nor the desk, …– And don’t get between them!

• Talk to (multiple) individuals, or at least to the back of the room

• Vary the tone and level of your voice• Use “normal” language

Getting through to the audience• Use repetition

– Remember that with a talk, people cannot “refer back” to earlier comments

• Use examples– Don’t get bogged down in

abstractions and generalities– Never present the details of proofs– Feel free to say “more details are given

in the paper/notes”

Know your audience• Scientists (or business people,

or the general public)– Will be interested only in general results

• Computer scientists– Use notation carefully and focus on the

problem• Theoretical computer scientists

– Will want to know exactly what your contribution is

• Experts– Will want to know how your work beats

theirs!

Timing

• Never over-run your allotted time– Talks which are too short are always better

than talks which are too long

• Be aware of how long you have, and stick to it

• Design multiple exit points, or identify material that can be skipped– Cut out details first

• Make sure you’re aware of the time

Handling nerves

• Everyone gets nervous• Make your nerves work for you

– Be animated: show them you care!

• But be prepared too– Deep breathing– Know your introductory “speech”– Use written reminders if necessary– Bring water, so you can pause and

re-group when necessary