Kanji for “Speak” and “Speech” - 話しor 話?

More and more people, even native Japanese speakers, misuse the Kanji character for “speech”.
When “話” is used as a noun, there is no “Okurigana” after the character. In other words, there is no “し” following the Kanji character. For example,
The teacher’s speech = せんせい の 話
However, when the character is used as a verb, the Kanji character needs to be followed by “し”. For example,
The teacher speaks. = せんせい が(は)話します
Since anyone can write anything on the internet, we see wrong usages of words or grammer daily. Even famous writers write casually, and editers are not checking them all. This situation sometimes confuses language learners. One thing we can say is that information on the internet, including the language, is a mixture of wheat and chaff, and we still need to check new words in dictionaries.
Plus, this must sound contradictory, though, it is also true that we, language learners, need to be brave and use the language without worring too much about making mistakes.