What does 打开的书本 look like on Facebook?

On Facebook it is the design shipped in 16.0, shown above at full size. Older revisions are listed beneath it.

When did Facebook add 打开的书本?

Facebook first drew 打开的书本 in 1.0, released 2014年1月31日.

Meta Platforms, Inc. has shipped 13 versions of 打开的书本. Each is dated, so you can see when the design changed.

Facebook 2.1

This is the design Facebook introduced in 2.0, shipped again unchanged. It was not redrawn for this release.

✳ marks a release that redrew this emoji. The rest re-shipped the design unchanged.

What does 打开的书本 look like on Facebook?: On Facebook it is the design shipped in 16.0, shown above at full size. Older revisions are listed beneath it.
When did Facebook add 打开的书本?: Facebook first drew 打开的书本 in 1.0, released 2014年1月31日.
How many times has Facebook redrawn 打开的书本?: Meta Platforms, Inc. has shipped 13 versions of 打开的书本. Each is dated, so you can see when the design changed.