A Presentation on Presentation
http://www.physics.ox.ac.uk/CDF/Mphys/APonPGraduateSpeakingCourse.ppt
Todd Huffman & Laura Corner
December 11th 2014
“’T ain’t what you do it’s the way that you do it.
That’s what gets results”
James Young and Sy Oliver
Introduction
1. Learning about giving good presentations
2. Visual impact
1. How not to have any impact at all
2. How to have plenty of impact; just in the wrong way.
3. How to have effective visual impact
3. Encourage you to Develop your Presentation style
4. Also show you many things you should NEVER do.
5. Then show you that you can almost always do what you
should NEVER do…if you think about it carefully.
Introduction
The first thing to note is that the “slides” in this presentation that are in this format are
not meant to be shown on the screen – they are meant to be read as text.
The second point is that these notes are not meant to be prescriptive, but descriptive and
illustrative.
In general, I have created artificial examples as illustrations – there are plenty of good
and bad examples out there, and we have all sat through many good and bad
presentations. I have shown examples, usually as extremes, but without comment
regarding which extreme I prefer. In fact, it is sometimes helpful, in order to make some
specific point, to include a slide that is extreme in some way – if the rest of the
presentation is “good”, it will make a point.
The aim of the graduate seminars is to allow you to develop your presentational “style”.
This is something that is, or should be, unique to you, and will say something about you,
your personality, your subject and your competence. Nearly all of this is in the sub-text,
but it is there. A poor presentation of a fascinating subject may well fail to convince. An
exciting presentation of some rather pedestrian information may be very well received.
This is not to say that style is more important than, or a substitute for, substance, but it is
to emphasise that you owe it to your audience (who usually don’t have to sit there) to
make it is as easy as possible for them to understand your message.
So, the basic message of this “Presentation on Presentation” is that whatever appears on
the screen (Font, size, character, colour, placement, pictures, graphs, animation,
extraneous information…) should in all cases be the result of a conscious choice, and not
because it is the system default, or because you borrowed a slide from a friend.
Fonts
There are several choices to be made under the font banner, and all are important.
–
–
Style:
Serif or Sans Serif
Appearance: normal, bold, italic, underlined or combined
–
Size: small (8pt), medium (12pt), Large (16pt),
–
Colour: foreground (text) and background
Huge (20pt), Vast (24pt)
The next two slides give some examples – what do YOU like?
Hint: Get hold of a data projector, look at the screen in a large room, from the back.
Other issues – do you want to try odd fonts?
Gigi, Castellar, Script, Btradley Hand ITC …
Note: If you use any fancy fonts, you must embed them with the presentation, otherwise
you risk having a very different layout (Greek not turning out as Greek, for example,
makes a real mess of formula or Feynman diagrams). For PowerPoint, use
OPTIONS/SAVE/EMBED TRUETYPE FONTS.
Have a nice day
Have a nice day
(Times New Roman 14pt normal)
(Arial 14pt normal)
Have a nice day
Have a nice day
(Times New Roman 20pt normal)
(Arial 20pt normal)
Have a nice day
Have a nice day
(Times New Roman 20pt normal
)
(Arial 20pt normal
)
Have a nice day
Have a nice day
(Times New Roman 14pt normal)
(Arial 14pt normal)
Have a nice day
Have a nice day
(Times New Roman 36pt normal)
(Arial 36pt normal)
Have a nice day
Have a nice day
(Times New Roman 14pt italic)
(Arial 14pt italic)
Have a nice day
Have a nice day
(Times New Roman 20pt bold
)
)
Have a nice day
Have a nice day
(Times New Roman 20pt bold
(Arial 20pt bold
)
(Arial 20pt bold
)
Have a nice day
Have a nice day
(Bradley Hand ITC 20pt bold
)
(Gigi 14pt normal)
Have a nice day
Have a nice day
(Bradley Hand ITC 20pt normal)
(Gigi 20pt normal)
Have a nice day
(Gigi 36pt normal)
(Gigi 20pt normal
)
Have a nice day
Have a nice day
(Bradley Hand ITC 14pt normal)
(Bradley Hand ITC 20pt normal)
Have a nice day
(Bradley Hand ITC 36pt normal)
Have a nice day
(Bradley Hand ITC 20pt italic)
Have a nice day
Have a nice day
(Bradley Hand ITC 20pt normal
Have a nice day
)
Have a nice day
(Gigi 20pt bold
)
(Gigi 20pt bold
(Gigi 20pt normal)
Have a nice day
(Bradley Hand ITC 20pt bold
Have a nice day
Have a nice day
)
(Gigi 20pt italic)
)
Have a nice day
Have a nice day
(Arial 14pt normal)
(Times New Roman 14pt normal)
Have a nice day
Have a nice day
(Arial 20pt normal)
(Times New Roman 20pt normal)
Have a nice day
Have a nice day
(Arial 20pt normal
)
(Times New Roman 20pt normal
)
Have a nice day
Have a nice day
(Arial 14pt normal)
(Times New Roman 14pt normal)
Have a nice day
Have a nice day
(Arial 36pt normal)
(Times New Roman 36pt normal)
Have a nice day
Have a nice day
(Arial 14pt italic)
(Times New Roman 14pt italic)
Have a nice day
Have a nice day
(Arial 20pt bold
)
Have a nice day
(Arial 20pt bold
)
(Times New Roman 20pt bold
)
Have a nice day
(Times New Roman 20pt bold
)
Slide Background
There are many different backgrounds from which to chose. As always, you need to make
a choice, and that choice needs to be deliberate. In making your choice, consider the
following point (and it is really the only point).
How will my choice of background help my audience understand my
message?
The next two slides give some examples (several per slide, so that you can compare).
Background with Washout
• Can still “see” the picture
• and the text reasonably clearly
• … but still distracting?
Making a point
• Full text
•
Without the Higgs mechanism, all
of the particles in the Standard
Model (quarks, leptons, gauge
bosons) are massless. What the
Higgs mechanism does,
respecting the underlying
symmetry of the Standard Model
while spontaneously breaking that
symmetry, is to give all of the
particles and the weak gauge
bosons mass, as well as
protecting the masslessness of
the photon. A physical
consequence of the Higgs
mechanism is that there is one
massive scalar field that cannot be
absorbed in the masses of the
other particles, and this is the
Higgs boson.
• Bulleted text
• Unbroken SM
– Quarks, leptons massless
– All gauge bosons massless
• Higgs mechanism
– Respects the underlying
gauge symmetry
– Spontaneous symmetry
breaking
– Quarks, leptons  mass
– W,Z  mass
– g remains massless
• Consequence
– Physical scalar field
• The Higgs Boson
Making a point
• Full text with emphasis
•
Without the Higgs mechanism,
all of the particles in the Standard
Model (quarks, leptons,gauge
bosons) are massless. What the
Higgs mechanism does, while
respecting the underlying
symmetry of the Standard Model
as well as spontaneously
breaking that symmetry, is to give
all of the particles and the weak
gauge bosons mass, but
protecting the masslessness of
the photon. A physical
consequence of the Higgs
mechanism is that there is one
massive scalar field that cannot be
absorbed in the masses of the
other particles, and this is the
Higgs boson.
• Bulleted text with
emphasis
• Unbroken SM
– Quarks, leptons massless
– All gauge bosons massless
• Higgs mechanism
– Respects the underlying
gauge symmetry
– Spontaneous symmetry
breaking
– Quarks, leptons  mass
– W,Z  mass
– g remains massless
• Consequence
– Physical scalar field
• The Higgs Boson
The history of the neutrino
Dear Radioactive Ladies and Gentlemen,
4th of December 1930
As the bearer of these lines, to whom I graciously ask you to listen, will explain to you in more
detail, how because of the "wrong" statistics of the N and Li6 nuclei and the continuous beta
spectrum, I have hit upon a desperate remedy to save the "exchange theorem" of statistics and
the law of conservation of energy. Namely, the possibility that there could exist in the nuclei
electrically neutral particles, that I wish to call neutrons, which have spin 1/2 and obey the
exclusion principle and which further differ from light quanta in that they do not travel with the
velocity of light. The mass of the neutrons should be of the same order of magnitude as the
electron mass and in any event not larger than 0.01 proton masses. The continuous beta
spectrum would then become understandable by the assumption that in beta decay a neutron is
emitted in addition to the electron such that the sum of the energies of the neutron and the
electron is constant...
I agree that my remedy could seem incredible because one should have seen those neutrons
very earlier if they really exist. But only the one who dares can win and the difficult situation,
due to the continuous structure of the beta spectrum, is lighted by a remark of my honoured
predecessor, Mr Debye, who told me recently in Bruxelles: "Oh, it's well better not to think to
this at all, like new taxes". From now on, every solution to the issue must be discussed. Thus,
dear radioactive people, look and judge. Unfortunately, I cannot appear in Tubingen personally
since I am indispensable here in Zurich because of a ball on the night of 6/7 December. With my
best regards to you, and also to Mr Back.
b energy spectrum
Your humble servant
W. Pauli
How many words? What about formulae?
There are essentially two extreme views about the purpose of the slide.
a) It is to help the speaker to remember all of the points that need to be mentioned.
b) It is to help the audience identify the crucial facts from the stream of consciousness
that issues from the speaker.
Both are valid, but lead to rather different styles of slide. The next few slides illustrate
this point.
Mathematical formulae present several problems. PowerPoint, in particular, is not very
good at them (it was not really designed for scientific presentation). Very long or
complicated formulae will need a lot of explanation if they are to be understood by the
audience – even if they are “well-known”. Detailed (theorem-like) derivations are likely
to be difficult to follow unless taken slowly.
In all of the above, there are circumstances in which either long text (e.g. a quotation) or
a complicated formula (e.g. the key result) needs to be presented. When this happens,
think about how the attention of the audience can be drawn (through highlighting or other
means) to the bits that are really important.
Formulae
• Simple formulae in PowerPoint
y=mx+c
y=mx+c
y=mx+c
• Or in Microsoft Equation 3.0
y  mx  c
• Or Mathtype 5.0
y  mx  c
Note:
PowerPoint 2010
is somewhat better
at formulae
Complicated Formulae
Pn  n e  

 
cos sin sin 

4c s c c  s s s  2c12c23 s12 s23s13 cos sin
2 2
13 12
2 2
12 23
2 2 2
12 13 23

 8c s s s c12c23 cos  s12 s13s23
2
13 12 13 23
 4c s s
2 2 2
13 13 23
1  1  2s  
sin 
2
2 m1 3L
4E
2
13
 8c s s
m32 1L
4E
2a
2
m31
 sin sin 
sin sin 1  2s 
cos
 8c c c s s s sin  sin
2
13 12 23 12 13 23
2 2 2
13 13 23
m32 2L
4E
2
2 m2 1L
4E
m32 2L
4E
m32 2L
4E
m32 1L
4E
m32 1L
4E
m22 1L
4E
m22 1L
4E
2 aL
13 4 E
a =22 GFneEn = 7.6 10-5 r E
Where is the electron density ; r is the density (g/cm3) ; E is the neutrino energy (GeV)
cij=cosqij, sij=sinqij
(Richter: hep-ph/0008222)
m22 1L
4E
A Bit of Animation
Pn  n e   4c s c c sin

2 2
13 12
2 2
12 23
 
3-flavour expression
2
2 m2 1L
4E
 
cos sin sin 

4c s c c  s s s  2c12c23 s12 s23s13 cos sin
2 2
13 12
2 2
12 23
2 2 2
12 13 23

 8c s s s c12c23 cos  s12 s13s23
2
13 12 13 23
m32 2L
4E
2
2 m2 1L
4E
m32 1L
4E
 1  1  2s  
sin sin 
 8c c c s s s sin  sin 
sin sin 1  2s 
 8c s s cos
2
 4c132 s132 s23
sin 2
m123L
4E
2
13 12 23 12 13 23
2 2 2
13 13 23
m32 2L
4E
a =22 GFneEn = 7.6 10-5 r E
2
13
2a
2
m31
m32 2L
4E
m32 1L
4E
m32 1L
4E
m22 1L
4E
m22 1L
4E
Matter
Effects
m22 1L
4E
2 aL
13 4 E
CP-Violation
Where is the electron density ; r is the density (g/cm3) ; E is the neutrino energy (GeV)
cij=cosqij, sij=sinqij
(Richter: hep-ph/0008222)
Pictures and Plots
Pictures can enliven an otherwise pedestrian presentation, but it can become tedious if
this reduces to the level of “here are some snaps I took while on holiday”. A montage can
look quite impressive, and help give the audience a real “feel” for the issues. The
eye/brain combination is a fantastically fast “pattern recognition” machine, and so you do
not need to spend a long time on straightforward pictures. However, for each picture
shown, you should at least indicate (with a caption/title and/or in words) what is shown
and why you have shown it.
Plots, on the other hand, are the very heart of a physics presentation (yes, and that
includes theory!) It is very difficult to think of any subject that would not be made more
clear to the audience than a well-chosen plot. Given their importance, then, it is
surprising how often plots fail to make the impact that they should. Often, this is because
one or more of the following obscure the meaning …
– The plot is too small
– There is no title
– The axes are unlabelled, or the labels are unreadable
– The scales are unreadable or missing, as are the units
– There are a lot of extra “lines” that are irrelevant to the point being made
– The plot was originally in colour but is now in B&W
– The plot itself is meaningless (many “double log” plots are meaningless, as are
many “data-montecarlo” comparisons)
Pictures
Sakharov
The RAL site with the 2nd target station and diamond
The 160m long NA31 decay
tube and helium tank
Me with Lord Sainsbury and
the VC of Sheffield in the
Boulby mine in North
Yorkshire
The Sun by the SoHo satellite
Plots
Plots
A tip with pictures and plots
• Photographs and figures
can take up a lot of
space. The size of the file
can be reduced
dramatically by
compressing pictures and
plots – this file, for
example, went from
25MB to 4MB after
compressing all pictures!
Animation
There are several different types of animation.
In-Slide Animation (revealing the contents of a slide in stages) can be very effective in
making a point. It can also be very irritating to the audience – a kind of striptease.
Between-slide Animation (slide transition) can be used to emphasise, highlight or add
further information by duplicating the slide, and making the two slightly different. [This
can be different with dissolve.]
Embedded clips (Quicktime, Realtime, video) can be very illuminating, but beware –
unless you can use your own laptop, it may not work as you expect when transported to a
different computer.
Remember that using animation may slow you down – you keep having to return to the
laptop/console to activate the next bit of the slide (unless you have a remote mouse). You
can use the timer to activate the next bit automatically, but again this is likely to be
different on different computers, and requires very careful timing of the words – it
becomes a “play” and not a discourse.
As with everything else, it is up to you. If you like it, and you think it helps the audience,
do it, but don’t overdo it (unless you wish to make some specific point that requires
overdoing it, of course).
A lot of Animation
• Here is a line of text
– And another
• And another
• And Here is some
more
– And more
• And more
The Structure of a Talk
I Keep Six Honest Serving Men …
Rudyard Kipling
I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who.
The Structure of the Talk
The Structure of a talk is important, and should “flow” naturally. How you make this
“flow” occur depends upon many things, some to do with the subject of the talk, but
others to do with the length of the talk, the nature (and size) of the audience, and perhaps
also the nature of the auditorium and equipment. Apart from the doggerel from Kipling
above, there is another easily memorable piece of advice (originally given to me as
guidance for writing my thesis) – say what it is you are going to say, say it, and then say
that you have said it! In more conventional terms, the talk should have most (usually all)
of the following.
Title [The title should be informative, enticing and give an idea of the style]
Who gives the talk [where you are from] [when and where the talk is being given]
(Note: update this last field – nothing annoys an audience more than the impression that
they are being given warmed up leftovers!)
Outline
The talk itself [If a long talk, perhaps some “chapter headings” from time to time]
Summary and/or Conclusions
Note that people can only absorb so much information without a pause for breath. For
any talk longer than a few minutes, and particularly for a “lay” audience [i.e. those not
already expert in the field], break up the flow of technical detail with relevant asides,
anecdotes, “soft” information, jokes, etc …
Example: After working through, say, a slide full of mathematics, tell the audience
something about your feelings when you first completed the calculation “When I reached
the end of this calculation, I can tell you, I needed a pretty stiff G&T”. This provides a
pause, and also reminds the audience that this is actually hard work
TITLES
• A Measurement of X
• In Search of X
• The Joy of X
• Much Ado About X
• X
• X: A Personal Journey of Discovery
Who Am I?
Todd
Todd Huffman
Brian Todd Huffman
BT Huffman
B Todd Huffman
Dr. Todd Huffman
Doctor BT Huffman
Doctor BT Huffman
C.Phys., Ph.D., M.Sc., B.S.E.E., M.A.
Adventures in the Quantum Kitchen
E. Picure
The Escoffier Institute for Quantum Gastronomy
delivered to the
International Conference on Quantum Gastronomy
Bakewell, UK
1st April 2009
“If music be the food of love, play on. Give me excess of it;”
Twelfth Night, William Shakespeare
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Outlines
•
•
•
Start
Middle
End
•
•
•
Start
– Day 1
• Hour 1
– Minute 1
» Second 1
– Day n
• Hour n
– Minute n
» Second n
Middle
– The First Mile
• The second furlong
– The third chain
» The fourth rod
– The last Mile
• The last furlong
– The last chain
» The last rod
End
– Of Civilisation
• In Europe
– As we know it
» Amen
Outline of talk
• Introduction
– Overview and status
• Recent Progress
– Experimental setup
– Data taking
– Analysis
– Results
• Summary and Conclusions
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Adventures in the Quantum Kitchen
E. Picure
The Escoffier Institute for Quantum Gastronomy
•
Introduction
–
International Conference on
Quantum Gastronomy
•
Recent Progress
–
–
–
–
Bakewell, UK
1st April 2009
•
Overview and status
Experimental setup
Data taking
Analysis
Results
Summary and Conclusions
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Examples of Boxes and Bullets
• Newtonian Mechanics
– Adequate for v<<c
• Special Relativity
%
Deviation from
Newtonian Mechanics
– Essential for vyc
 For vJ0.01c
– Deviation > 5 × 10-5 %
– Relativity important
Deviation
0.00005%
0.01c = 3 × 106 m/s or 1.08 million kph
v/c
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Sample Table
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Summary and Outlook
• Summary
– Status quo ante
– Innovation
– Result
– Impact
• Outlook
– What needs to be done
– What I will do
From Presenting Science, Oxford University Press 2010, © Çiĝdem İşsever and Ken Peach
Jokes and Cartoons
•
Humour can make a serious point –
properly done, it lodges in the brain
a “hook” (the joke, cartoon or
amusing image) that should recall
the association – the serious point
you were trying to make.
•
Note that it has to be relevant –
telling an “Englishman, Irishman and
Scotsman” joke is a distraction
(even if not offensive).
•
One well-known example is the
famous “penguin diagram” (top right)
– the story goes that John Ellis had
a bet with someone (Melissa
Franklin in a pub in Geneva) that he
could get the word “penguin” into his
next published paper … illustrating
the diagram with a penguin (bottom
right) always helps …
copyright Peter and Barbara Barham
Posters
•
Posters follow the same rules as for a presentation, i.e. there are no rules
that cannot be broken … but … you need to get your message across, so
– Clear, readable, concise
– Well laid out, with a clear “flow”
– Engage the audience
This famous 1st World War poster was designed by
Alfred Leete (1882-1933) originally for a magazine
cover and then adopted as a recruiting poster.
A “typical” physics poster
Posters (continued)
• Portrait
1
3
or
2
4
Landscape?
1
2
4
3
Posters
(continued)
Here is one that my
predessor quite liked
But still a lot of words
Posters
(continued)
Here is my own most
recent poster
Many fewer words
… and finally - DRESS
Too Dressed up or too dressed down will be noticed.
Do you want to be noticed for your Pink Socks and Orange striped
trousers or because you have given a brilliant talk which the audience
understood?
Maybe you do. Do it for a reason it might be OK.
But in general  Dress slightly better than your
audience will dress.
Some final thoughts
There are no absolute rules in presentation – there are always circumstances in which any
particular rule can (and should) be broken if it creates the desired effect and helps the
audience understand better the point that is being made.
However, always remember that it is for the benefit of the audience that the presentation
has been prepared. There is no excuse for making a sloppy, ill-prepared, random
presentation.
Treat a presentation as a theatrical performance – rehearse it several times. If it is an
important presentation (even if very brief – for example, the 5 minute “presentation” at
the start of a job interview) ask the opinion of a (good) friend – one who will tell you the
strengths and weaknesses of your draft.
Remember, if the people at the back cannot hear you, they probably will not understand
the presentation – if a microphone is provided, make sure that it is properly fitted – up
high, close to the throat. If you turn to the right (left) to look at the screen, make sure that
the microphone is also biased to the right (left). If using a standard microphone, do not
speak directly into it, but allow a few centimetres (if possible, try before the seminar).
Use of laser pointers – practice where you want to point, and keep still – laser pointers
waving all over the place are very distracting – use it to POINT to what you wish to
emphasise.
Rules to give an Excellent Presentation
“There are no Rules.”
There seem to be only guidelines.
I mostly agree but there is one
VERY important rule!
Graduate Student Seminars
Group A [Todd Huffman]
Christopher Arran
[CA]
Thomas Hadavizadeh [TH]
Anita Nandi
[AN]
Mariyan Petrov
[MP]
Robert Shalloo
[RS]
Luigi Vigani
[LV]
Robert Williamson [RW]
Huibo Zhang
[HZ]
Group B [Laura Corner]
David Coplowe
[DC]
Mehpare Atay
[MA]
Nurfikri bin Norjoharuddeen [NbN]
Talitha Bromwich [TB]
Jonathan Burr
[JB]
Cees Carels
[CC]
Luca Cavalli
[LC]
Hannah Harrison [HH]
What you have to do
• Prepare a 10 minute talk on your experiment, or
what you have been doing, or what you expect to
do (send title to TH before Monday Jan 15th)
• Suitable to be understood by your class cohort (and
supervisors)
– Remember! They are Non-Experts!
• Practice talks – 30 minutes time available for each
person, including feedback – all members of the
group must attend!!!
• Final talks – 10 minutes + 5 minutes “discussion” +
5 minutes to set up the next talk – all members of
both groups + LC + TH to attend; supervisors &
others invited
Schedule
Wednesday [1115-1300]
Wednesday [1115-1300]
Fisher Room
Conference room
28/1 TH-A [CA,RS,AN]
28/1 LC-B [DC,MA,NbN]
4/2 TH-A [TH,MP,LV]
4/2
11/2 TH-A [RW,HZ]
13/2 LC-B [LC,HH]
LC-B [TB,JB,CC]
26/2 [Everyone] (Denis Sciama) 5/3 [Everyone] (Denis Sciama)
MA,NbN,TB,CA,RS,AN,TH
MP,LV,RW,HZ,JB,CC,LC,HH
http://www.phdcomics.com/comics/archive.php?comicid=847
The End
There are a few useful guides.
This one is available here
(apparently)
http://www.me.vt.edu/writing/csp.html
Some more books
“This author has hit the proverbial
nail on the head, sending much
needed advice to speakers in the
scientific community … With such a
wealth of information in such a
little book, it deserves a niche in the
briefcase of all scientists and
engineers interested in improving
their public speaking skills.” J.
Chem. Inf. Comput. Sci. (from
Chemical Abstracts Service)”
From our point of view, the book is
too prescriptive in some cases just
wrong (it advises writing out the full
text of your presentation in words
before you do anything else).
“A horrendous book by my
former professor...., Upon
reading and studying this guide, I
wholly expected that it would
provide me with knowledge and
confidence in presentations. I was
unfortunate enough to encounter
Dr. Walters as a professor
AFTER reading this title, and am
appalled at his lecturing skills.
One would think that he would
take a few hints/pointers from his
own text and apply them to his
lecturing. “
(Review on Amazon)
Each chapter starts with a
“story” illustrating
something that went wrong
with a presentation, and
then trying to extract the
lessons from it.
Probably closest to our
approach … basically
sound
This is a new book from
professional communicators
(5 easy steps to the perfect
presentation) and claims to
be the result of many years
of experience running
courses. A bit too “slick”
for our taste – in general,
physicists are a bit wary of a
presentation that is too slick.
A
new
book
Available now in all good
bookshops
… and discounted on
Amazon