Hi there, The second structure is the correct one in this case. 'interested in' doing something talks about hobbies and topics which you enjoy learning about in general, for example: I am interested in French poetry I am interested in dancing It is also used to talk about things which you would like to do: I am interested in joining your reading group 'interested to' is only used with certain verbs - see, hear, find out, learn - and it is usually used to say that you would like to find out more about a topic, or alternatively that you are even quite surprised about something: I was interested to find out that Ronaldo grew up in a poor area I was interested to see the culture in India In your sentence, you would have to use 'interested to', because you are talking about the fact that you may want to hear more about the fact that someone's English has improved. I hope this helps!

It's OK to use "interested to + base verb" when "interested" means "curious". Your sentence would be correct if you put it in the simple past: "I was interested to learn that your English has improved." When "interested" means "have an interest", then you must follow it with "in + noun/-ing" e.g. "I am interested in learning German" Many students write interested + to + base verb in error.

Hi Paul! Good question. The first one is a very common form, however "I am interested in learning..." indicates an interest in a currently unknown or future event, therefore it couldn't be followed by the past perfect "has improved". Correct example: "I'm interested in learning if your English improves." (This sounds a bit rude though. Haha.) The second one is what we would use in this situation, because 'to learn' Can be used with a past perfect formation, either in speech or in writing. I hope that helps. :)

They are both valid, though they mean two different concepts. Interested + in is for something that lasts for a long time. E.g. I'm interested in sport. Interested + to is for something that is like a unique event. E.g. I'm interested to know when we're leaving.