How to structure your BIG ideas in presentations

Did you know that they way we convey ideas to others can be compared to the decay of radioactive substance? Thought not, let me explain.

A half life

The scientific definition of a half life (not the computer game!) is the length of time it takes for a radioactive substance to decay… well, for half of it to day. The way radioactivity works means that, as there is less and less of the radioactive substance, the rate of decay slows down, so it takes longer and longer for whatever’s left to fall apart.

It works the same when we’re trying to share ideas. It’s also an interesting  concept in productivity that explains why we shouldn’t keep jumping from task to task.

But here, I’m going to explain why it’s important to think about Idea Half Life (IHL) in presentations… or in fact in any type of communication where you’re passing on lots of Big Ideas (BIs).


Here’s where the problem lies

These graphs should help.

Suppose you give people your first BI and the amount of effort it takes for people to deal with it is shown in the purple line 👇

As you can see, the amount of effort required goes down over time as people get used to the idea. 

So far so good.

But what happens if you go on to introduce BI2 (your second big idea)?

If we add it in a sort of dull yellow colour, the graph starts to look like this…

I’m pretty sure you can see the problem. None of the effort under the purple line is available to handle the effort needed to deal with the yellow line!

If BI2 is a biggie, then this might be a bit of an issue.

If you’ve got more than two BIs in your presentation (or whatever method of communication you’re using), the problem compounds because these bits of effort are cumulative.

It could mean that by the end of your presentation no one has  any head space left for the effort needed to handle BI9!

In other words, you’re potentially wasting your time and melting your audience’s brains.

I can’t just not tell people things! What can I do?

There are things you can do and some of them are pretty easy.

The obvious one, of course, is to tell people fewer things, which by the way, is absolutely allowed!

The second best option is to split things up into small enough chunks for the half life of your BIs to have decayed before you start again.

It’s one reason why online courses (including ours) have lots of small chapters, not one big one. 

So now we’ve had a look at the basics, let’s have a look at some practical ways you can apply this theory.

Create signposts for your audience

You might know you’re moving on from BI3 to BI4, but it’s not obvious to your audience automatically.

Remember how novels have chapters in them to signpost that they’re changing scene, location, time, or characters, etc? Well, you can do the same with your presentations by thinking of each BI as a chapter.

How would you indicate the end of a chapter? Probably by having a big chunk of white space in the book (that is, you’d start the new chapter at the top of a new page, not following immediately on) and you’d almost certainly have a chapter heading. If you apply that logic to a presentation you might have a blank (black) slide and then a new, fresh-start slide.

Be blatant. Tell people. Show people. Hit them over the head with it!

Change the media you use

Although this is related to the previous idea, it’s got merit on its own, too.

When you move from BI5 to BI6, change the media you use.

For example, in my training courses, I shift from slick slides to what look like impromptu sketches on a flip-chart. (It isn’t impromptu, of course, I’ve rehearsed what looks like making-it-up-as-an-idea-occurs-to-me.)

At the very least, consider changing the colour-scheme of your slides, so that people know where they are, or if you’re happy to have ugly slides, put a running header along them so that people see the words “BI6” in the bottom left corner of all the BI6 slides. Then put “BI7” in the bottom right for the appropriate slides.

Why put them in different places?

Remember what I said about being blatant and hitting your audience over the head?!

Mix it up

This one’s obvious when you think about it. If BI3 is an absolute whopper and BI5 is also going to melt people’s heads, think about making sure BI4 is either (or both!):

  • an easier one
  • about something very different

Both options are intended to give your poor, battered audience time for the half life to decay a bit more before they get hit with another BI!

Be devious

There’s a lot more to be said, but I won’t. Why not? Because you’ve probably got enough to be going on with now and if I give you a fourth Big Idea you’ll pay less attention. The important thing now is to think about the three ideas you’ve just been given and:

  • reeallllllly think about them
  • figure out how to apply them, test them, embed them in your work
  • move on, so that your head-space is clear for your next task!

Actually, there’s one more thing you should do… comment and/or share this blog! 😉

Dr Simon Raybould spent two and half decades as a research scientist and has also worked as an actor, lighting designer, teacher and fire-eater! He’s the author of three books on presenting, one of which became a best seller and two of which sank without trace.

He’s now one of the UK’s leading presentations trainers and designers. See more at and if you want some training by him see for his only public UK training this year.

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