Harrison looks at an 'eyelash mite' through a microscope to show an example of a bug that can't be seen by the naked eye.
Harrison explains that vampires aren't real, but vampire bats are and he teaches how they use their teeth to eat.
Harrison explains why some people are more scared of little animals than big ones.
Harrison explains how spiders make webs and why they are so strong.
Harrison visits the dentist and gets his teeth cleaned.
Harrison asks some kids what kind of animal teeth they would have if they could choose.
The answers in Gwen's are answered in the opening montage of 'Arthur Christmas'.
Walter sends Buddy to a service in his building which is performed underground.
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Harrison explains how dogs use bones and other chew toys to clean their teeth.
Arthur's brother, Steve, compliments him before asking him to leave Christmas Headquarters.
Sosuke first encounters Ponyo and frees her from the glass jar from which she is trapped.
The answer to Gwen's question about Santa Claus' age is answered in the opening montage of 'Arthur Christmas'.
A team of people make the decision to delete Christmas, so as to avoid the events of 1816.
Harrison explains which human teeth are used for meat and which are used for plants.
Harrison explains what happens if you don't clip your fingernails.
Harrison raps about the life cycle of a butterfly.