Here are past National Latin Exams with the correct answers and explanations. The NLE website (nle.org) has past exams of every level. Links below are helpful resources to fill in the blanks that Henle does not cover in the purple book. There are also practice quizzes you can take on the NLE website.
I recommend a Challenge A student take the Introduction to Latin exam and a Challenge B student (who has had
Challenge A) may take the Latin 1 exam. If your student is coming into Latin in a later Challenge year without prior Latin study, start with the Introduction-level exam.
You can download past exams for free to practice before you read my supplement.
Parents: I always recommend you skim/read the websites to be sure it is suitable for your student.
National Latin Exam Folder (Google Drive)
2012 Introduction to Latin National Latin Exam with Answers and Explanations
2021 Introduction to Latin National Latin Exam with Answers and Explanations
There are imperatives on this test-review them before taking it.
2022 Introduction to Latin National Latin Exam with Answers and Explanations
Grammar Notes:
Please note, it is necessary to know for the NLE that the imperfect tense may be translated I was verbing, I verbed, I used to verb, I began to verb, and I kept verbing.
Only the first two are mentioned or taught in the Henle Purple Book, but all of the five listed above are commonly taught in most Latin textbooks.
Resources
Ancient Roman Homes and Room Names (advanced)
Cardinal (Counting) Numbers: Video
The cardinal numbers are grammar paragraph #112 on page 28 in the Henle Blue Book.
Major Gods and Goddesses, Symbols, and Patronage
More Gods and Goddesses' Symbols
Preposition List (Most Common)
William Stearns Davis's A Day in Old Rome
This is an old book, a little dry and harder to read, but it's really reference material and is valuable read in small chunks by topic, and not cover-to-cover.