Yes. The hard copies of the 1st edition (2012) Essentials books are sold out, but you can still purchase them in PDF format, with usage licenses for both individuals and schools available.
We plan to continue offering First Edition Essentials books in PDF format for the time being, so that those who would prefer to continue teaching the older version may do so.
The other materials used with the 1st Edition of Essentials, such as flash cards and reference charts, are used with the newer editions of Essentials as well and are still available on our webstore. New editions of these materials will have minor changes and additions, since we continue to refine and clarify what we teach about these concepts, but they can still be used successfully with Essentials 1st Edition.