The Ptlls assignments are being documented right now, for an overview check out this Ptlls assignments link and then there are links to each assignment.

The homepage holds all the latest posts and you can also search the site using the box at the top right or by browsing through the category and tag archives in the right sidebar.

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There are also links to resources elsewhere on the web.

Other popular resources here are:

The difference between level 3 and 4 post.

A quick Ptlls reading list.