Inference isn't really a skill. There's no part of the brain that does your inferring for you. Either you have sufficient conceptual and real-world knowledge to 'see' a meaning or you don't. Spend less time practising inference and more time teaching concepts and background...

For example, if I know enough about characterisation and know some relevant history, I can infer that Priestley uses Mrs Birling as an example of the outdated feudal attitudes that perpetuate social inequalities. If I understand that writers might use light to symbolise truth,

I can infer that Scrooge's attempts to extinguish the light of the first spirit is Dickens' way of suggesting that confronting truth is painful so we resist it.

If I don't have the background, these meanings will not present themselves. Someone will have to tell me.

If you liked this tweet please look out for my new book, co-authored with my good friend and colleague @samgibbs1, provisionally titled:

The Trouble with English: improving secondary English provision through effective CPD and rigorous curriculum design.

It's due out in spring