Newspapers are excellent sources for reviews of performances. Reviews typically appear the day after opening night.
Sometimes, reviews will also exist in scholarly theatre journals.
Here are sources you may find performance reviews.
For your Group Research Assignment, you will be collaboratively researching a movement in theatre history. You will want to find and read about the movement in books and encyclopedias to get a good overview of the movement, its importance, features. From there you will need to identify major theatrical works, playwrights, and key figures. You should favor high-quality, "good" sources written by theatre researchers and experts.
Below are sources you can consult to find the information you need.
Scholarly sources include articles published in peer-reviewed journals as well as books published by academic publishers and university presses. You can find some of these sources in the Library Catalog, but there are databases you may find helpful, too. Here are a few of the best for theatre.
Use the same search tips and techniques in databases that you use to search the Library Catalog.
Here are a few books that include information about the theatre movement known as Realism. You may find some more useful than others are you work on your project. These books will get you started, but won't be enough on there own.