You cannot be responsible for how a person uses the information you present to them, but you are responsible for delivering it in such a clear and helpful a way that they can use it if they want.
The human mind - like a satellite dish - is designed to take-in as well as give-out information. Anyone who has to present information to others should make sure that the 'taking-in' bit of their presentation - the "Will an audience get it?" bit - has had as much attention paid to it during preparation time as has been paid to the material itself. One way to achieve this is to package some ideas in such a way that audience members get the chance to unpack them for themselves.
Just as small children ask for help with unwrapping only when they're completely stuck, and then the instant they see how to continue insist that the package is returned to them, so audience members of all ages and all abilities will act in the same way, and have fun in the process.
"But surely, (I hear you saying) those who fail in the attempt will be disgruntled?" True. But no matter what methods you use, there will always some listeners who can't or wont take in what you say or who need a period of quiet reflection before the meaning sinks in.
The fastest learning is done when your Material, Oratory, Volume and Energy Further listeners' knowledge, Underline their receptiveness and Nudge them towards thinking creatively for themselves. In other words, you should aim to MOVE your listeners and make their learning FUN.
The best way to move people is speak straight to their eyes.
I'm not talking about the common notion of making eye contact. That only makes sense if you are working one to one or with a small group. No. I'm talking about animatedly looking to people's eye-level so that you can see instantly how far your voice must travel before it can gain attention.
This automatically causes you to hold your head up and allows your vocal and facial muscles instinctively to widen your jaw, teeth and lips (the rim of your vocal tannoy) and inform your voice what tone, texture, colour and sheen it should display in order to bend people's minds to what you have to say. To this end, it is always helpful to get to the place you are going to work in well before the audience does so that you can see its dimensions or at least have had a scale plan sent to you in advance.
The other element that will determine how audible and interesting you will be is your own level of engagement with the message.
When you are committed to an idea, your mind and body shape up to what is required of them and regulate communication to fit listener absorption time. Incidentally, the most intractable of minds can often be enticed to engage if you allow the flow of your words to fluctuate from time to time so that it seems as if you are sharing their moment of conception with your listeners. A final thought. Egos bruised by a failure to unpack your information can usually be soothed by ending with quotes from eminent sources. One that would suit those who just needed longer to tussle with the problem comes from Physicist, Joseph Polchinski: "First try to do something and if you fail, try to prove that it's impossible."
The second, from Philosopher, Alan Wilson-Watts, "Problems that remain persistently insoluble should always be suspected as questions asked in the wrong way." should allow seriously disgruntled participants to go away blaming their inability to access the information on your faulty packaging rather than on their lack of dexterity.
"Touchť," you might say.
Ahh, but Ö. There is always a chance that those words might also set them thinking about what the right question could be!