I find it helpful to teach the differences between the meanings of let/enable/help/make (as causative verbs) together, because there are several areas of possible confusion. The most common mistake, in my experience, is the overuse of "let". Here is my simplified explanation:
1. Permission - "let"
e.g. My boss lets me drink beer at work. He is very relaxed.
[My boss does not stop me from drinking beer, but he does nothing to help me drink beer.]
2. Make something possible - "let" / "enable"
a) My boss enabled me to go on holiday next week by reorganising the duties within the team.
[My boss did more than "let = permit" me. He did something real to make my holiday plans possible. I cannot use "let"]
b) The internet enables us to communicate / lets us communicate with each other easily.
[The internet is a thing that operates, not a person. I can also use "let" with this meaning when the subject is a thing.]
3. Make a real contribution - "help"
a) My boss helped me (to) finish my work on the day before my holiday. He spoke to several customers who I usually deal with.
[My boss did not finish all of my work for me but he did some of it.
b) Vacuum cleaners help to keep houses clean.
[Vacuum cleaners are not the only things that keep houses clean but they make a contribution.]
4. Produce a result - "make"
a) A natural result: "My boss gave me a big bonus thus year. This made me very happy.
b) A forced result: "My boss made me work on Sunday last week - he is a tyrant."
If anyone has any feedback on the quality and accuracy of these explanations, I would be grateful. Also, if anyone can recommend any resources with exercises on the above issues, I would be grateful. I have found various exercises on causative verbs but they don't deal with the two usages of "let" above or the usage of "enable". They also include causative uses of "get" and "have", which I would prefer to teach separately.
Thanks for reading.
One addition to the list:
A strong boss or teacher "makes" her employees or students do things; a nice boss or teacher "asks" his employees or students to do things.
The teacher made the students stand up="OK, everybody stand up!"
The teacher asked the students to stand up="Could everybody stand up please? Jill, you're not standing. Would you like to join everyone else and stand up?"
You ask your friends or colleagues to do things. If they are equal to you, you usually won't "make" them do something--although occasionally you might.
You ask your boss to do something.
"Sir, please sign these papers when you have the chance."
Also, something to emphasize:
After "make" and "let", DO NOT say "to".
Right: "I made him eat."
Wrong: "I made him to eat."
After "help", it is OK to say "to", but most Americans strongly prefer NOT saying "to".
OK: "I helped him to eat".
Better: "I helped him eat."
After "enable" and "ask", you HAVE TO say "to".
Right: "I enabled him to eat."
Wrong: "I enabled him eat."
I'd focus more on the grammatical structure for these, and less on the definitions. This leaves us with only four verbs in total to work with: make, help, let and have.
make me work / help me work / let me work / have me work
I realise texts want to add "get" into the "causative" category, and I'd put this in a different group: [verb A] [someone] to [verb B]
get me to work
So this extra group includes enable and get, as well as ask, convince, encourage, allow, inspire, and so on... if there's a difference, I'd say the second group doesn't guarantee the desired action in the way that make, help, let and have do.
Thank you for your kind contribution, Chris.
The rules on the usages of the various verbs are the same in UK English, including "help".
I would not classify "ask" as a causative verb, which is the focus of this discussion. However, the contrast between "make" and "ask" is a good one.