-Student sessions will be held on Tuesdays from 11-12 and Wednesdays from 3-4. (You only need attend one session.) You should see these sessions as opportunities to clear up lingering issues from material we've discussed, and help get a better footing for what we'll be doing the next week. It would be smart to make a serious start on that week's homework, for instance, before the session.
+You should see the student sessions as opportunities to clear up lingering issues from material we've discussed, and help get a better footing for what we'll be doing the next week. It would be smart to make a serious start on that week's homework, for instance, before the session.
+
+There is now a [[lambda evaluator]] you can use in your browser (no need to install any software).
+It can help you check whether your answer to some of the homework questions works correctly.
+
+There is now a [library](/lambda_library) of lambda-calculus arithmetical and list operations, some relatively advanced.
+
+There's also a page of [[miscellaneous lambda challenges and advanced topics]].
+
+
+
+<!--
+ To play around with a **typed lambda calculus**, which we'll look at later
+ in the course, have a look at the [Penn Lambda Calculator](http://www.ling.upenn.edu/lambda/).
+ This requires installing Java, but provides a number of tools for evaluating
+ lambda expressions and other linguistic forms. (Mac users will most likely
+ already have Java installed.)
+-->