DS8 needs to develop a growth mindset. Preferably immediately. Before I send him to an unpleasant boarding school out of spite (joking).

I've read about praising effort but are there any good resources for him? A book or website he can do himself and then we can talk about it would be great.

There is no "working to learn" anything with him right now. He either knows it or doesn't. And if he doesn't know it he generally thinks it isn't really necessary anyway. He is 2e and is the type that will go on all about the life cycle of some obscure animal but then mess up the order of the months of the year. And then have a straight faced argument about why it really isn't important to know the months in order!!

He worked really hard two years ago on learning to read. Now he just thinks he will learn by reading books, watching documentaries, going to museums and on field trips. If it doesn't stick after that? Well then to him it probably wasn't important anyway.