“Grammatical Horrors” presents a series of sentences and short dialogues containing errors to be identified and corrected, choosing from several options. The app is embellished with original images created by Federico Mancini, a well-known illustrator of fairy tales and children's books.

Knowledge and correct use of grammar are fundamental in the learning process. The exercise of grammar rules allows you to develop logical skills, favors the adequate use of language and ultimately allows you to communicate and access knowledge.

The exercises are ordered by increasing difficulty, and contain phonological, morphological and syntax errors.

The execution of an exercise is simple and instinctive: each sentence presented contains several errors that can be corrected by touching the various 'parts of the speech' and selecting the correct word or punctuation mark in a title block; some sentences must be completed, inserting the missing elements. When you choose an option, the sentence is rewritten with the new element. The end of the exercise is signaled by touching a button, or occurs automatically at the end of a predefined time for each sentence.
At the end of each exercise, the app presents a brief feedback to comment on the result obtained, while any errors not identified (or added involuntarily by those who perform the exercise) are underlined in red. If the exercise has been completed successfully, you can automatically move on to the next one; otherwise, repetition is proposed.
Furthermore, after the end of the exercise, by touching the various parts of the sentence it is possible to see the grammatical analysis of each. A button shows the solution, i.e. the correct sentence.

The default progress of the exercises can still be altered, for example by selecting the next exercise even if the current one has not been "solved", or by going back to the previous sentence, or by manually choosing an exercise from the list.

The complete list of exercises (100, in total) is shown in a separate screen and presents the text with the errors and a series of symbols that indicate the main types of errors contained in the exercise. If you touch the symbols on the legend you can exclude / include the exercises that contain them. A button allows you to create lists of exercises chosen according to the set exclusions.
When preparing a list, the first exercise that is part of it is automatically selected for execution, but you can manually choose the exercise to start with. A custom list remains valid until it is replaced.

In many exercises, errors (and sometimes corrections and additions) can generate surprising and even comic results, for example in sentences where the wrong words differ only one letter from the correct ones, but with completely different meanings.
The app aims to offer a simple and pleasant tool to integrate and verify the learning of grammar and its rules.