Future tense used to start a presentation

[Buddy42]

Hello,
right at the beginning of a presentation or talk lecturers usually inform their audience about what they can expect to hear.
The lecturers know what they are going to tell their audience because they have planned their talk in advance.
Good morning, dear students
a) Today I'm going to tell you something about ....
b) Today I'll tell you something about...

I think
a) is fine because this is the lecturer's plan. The same goes with: "Today I'm telling you something..."
b) is neither a prediction nor a spontaneous decision, so it must be wrong. To me it sounds okay, though.

 

[SoothingDave]

It's fine.

 

[Skrej]

b) is neither a prediction nor a spontaneous decision, so it must be wrong. To me it sounds okay, though.

True, but those are not the only situations to use 'will' over 'going to'. 'Will' is also used for promises, for example.

Also, we can use both 'going to' and 'will' for near future predictions, especially when there is good evidence or signs to support the prediction. However, as you said, it isn't a prediction in this instance, but more of a promise.

Either one works here, as Dave mentioned. It just depends whether you consider it a promise or a prior plan, but it doesn't really matter since both work equally well.

 

[teechar]

The same goes for with: "Today I'm telling you something..."

No.
1- "goes with" and "goes for" mean different things.
2- "Today, I'm telling you something" is not used to introduce a lecture.

 

[emsr2d2]

Hello. Note that there is no need for an opening greeting.
Right at the beginning of a presentation or talk, lecturers usually inform tell their audience about what they can expect to hear. The lecturers know what they are going to tell their audience because they have planned their talk in advance. For example:

Good morning, dear students.
a) Today, I'm going to tell you something about ...
b) Today, I'll tell you something about ...

I think a) is fine because this is the lecturer's plan. The same goes with for no colon here "Today I'm telling you something...". I think b) is neither a prediction nor a spontaneous decision, so it must be wrong. To me it sounds okay, though.

Note my corrections and comments above.

Both a) and b) are possible. "Today, I'm telling you ..." is unnatural in this scenario.