As an AI language model, I don’t have access to specific books or their page numbers. However, I can provide you with ten tricky words from the Harry Potter series that are suitable for a six-year-old pupil. These words are commonly found throughout the series and can be introduced to young readers:

1. Wand - a magical tool used by wizards and witches to perform spells.
2. Quidditch - a popular wizarding sport played on broomsticks.
3. Muggle - a non-magical person who is not part of the wizarding world.
4. Gryffindor - one of the four houses at Hogwarts School of Witchcraft and Wizardry.
5. Hogwarts - the magical school where Harry Potter and his friends study.
6. Potion - a magical liquid with various effects when consumed or used.
7. Patronus - a positive force or guardian that can be summoned to protect against Dementors.
8. Diagon Alley - a hidden street in London where wizards and witches buy their magical supplies.
9. Quibbler - a wizarding magazine known for publishing unusual and often eccentric articles.
10. Hippogriff - a magical creature with the front half of an eagle and the hind half of a horse.

Please note that these words are not specific to chapter 23 of any Harry Potter book, but they are commonly used throughout the series and can be introduced to a six-year-old reader.