 I think in the early 90s you coined the term desirable difficulties, now these are obviously not the sort of things that would occur to students who would immediately think of them when studying for an exam or something. Could you just explain desirable difficulties? Well the notion of desirable difficulties is that refers to a set of manipulations that all have the property that they create challenges, a sense of difficulty during the acquisition process. That's the sense in which they're difficulties. They're desirable in a sense then they enhance long-term retention and transfer. So varying the conditions of learning or practice examples rather than keeping them constant and predictable, reducing, using tests rather than presentations as learning, interleaving the separate things to be learned rather than blocking practice on each thing at a time. There's a whole set of these that create this misimpression, actually I've just given you the desirable difficulties. They create the sense of difficulty but then are associated with better long-term retention. And really another way to put all this is a very old distinction going back to the 1930s between performance and learning. So performance would be like how accurate you are, how rapidly you can do something during the acquisition process. Learning is those changes and relatively permanent changes that will support your being able to recall, use this information later. That's what we would like to optimize. But what happens is we can confuse performance during the process as evidence of learning and many things that make performance go up very rapidly. Practice continuous feedback, keeping conditions constant and predictable, make performance go up really rapidly and then are associated with very poor long-term learning. And other thing that's made these results so important is various things where you ask people what helped you learn better, this condition or that condition, or predict how well you do on the test that comes in a week. It shows that people are really fooled by their current performance. It's not only unreliable indicator of whether learnings happen. It's sometimes exactly the opposite. So we're really at risk of misinterpreting whether we've acquired the skills and knowledge that we are intending to acquire. So on the one hand, it's never been more important to know how to learn because more learnings happen outside of formal supervision. We're on our own, we're at a computer, we're doing this, we want to learn some new tech feat for job purposes or whatever across the whole lifetime. So we need to know how to learn. But it's not easy. Our intuitions mislead us. A lot of the standard practices that we've been exposed to in schooling are not optimal. We would just natural for us to think, well, if our teachers did that, that's the way we should do it, and that's often wrong. So it's really, it's a critical kind of juncture of can people learn how to manage their, be effective stewards of their own learning? And that's an ultimate sort of survival skill. My name is Bob. I think about learning.