3) In a lesson, how would you illustrate and clarify the difference between these grammar points? Give detailed examples of the questions/graphics/timelines etc. you would use.
b) Going to vs. will for future plans.
c) Present simple vs. Present continuous.
There are four ways to express future ideas in English. We use the "going to", the present continuous, the "will" plus bare infinitive form, (the future simple), and, the present simple.
The future simple is commonly used to express a prediction, that is, a guess or a subjective opinion, about the future; when we've not made any definite arrangement, that something is probable, or likely to happen at the time of speaking.
If I asked you the question: who do you think will win the the football match? I'm guessing that you might say 'I think Liverpool will win', and you might also feel really confident about that. But I think even the most passionate football supporter would agree that the final result (of a football match that hasn't yet finished) can't be thought of as definite or something that has been arranged in advance.
In a similar way, we also use 'will' for decisions, offers, promises or threats that are spontaneous, or made quickly at the moment of speaking. The speaker hasn't decided before. If you saw the sun was shining outside, you might say 'It's a beautiful day, I think I'll, or I will, go for a swim later,' or 'maybe I'll phone my friends and organise a picnic'.
In all of these situations, the common link is that there are no definite arrangements for these events. No decision has been made before speaking.
Going to + bare infinitive, is sometimes used quite interchangeably with 'will'. This has a particular function for stronger predictions, perhaps when there's some present evidence to suggest something will happen: "You are a really good student, I think you're going to do well in your exams."
We also use this structure when we have a personal intention, or are making a resolution or decision to do something, as in, 'I'm going to stop eating so much chocolate this year'.
In a context where you have not only decided to do something but also made all the arrangements, sometimes referred to as 'diary future', we're more likely to use a present verb tense, the present continuous. the am/is/are + ING form of the verb, I "I am going out to the cinema tonight". We use this form for future events that are booked and already arranged, and which we consequently feel are definitely going to happen. It is generally in our control.
The present simple is used for events of the future that are not in our control, for example, the plane arrives at nine tonight.
A good way the explain the future simple to Ss is to ask them to look the word "will" up in their dictionary. Draw their attention to the noun form and they might have a better idea of the sense expressed when they use this form. Reassure them and say that the present continuous is commonly used. The will has quite a passionate sense.
I hope that helps a wee bit.