The Biggest, Bestest Time Ever! is the first book in the Mal and Chad series.
Summary[]
Mal is a super kid genius and Chad is a talking dog, but no one knows it. What's it like to be so extraordinary and yet so invisible? Not even Megan, Mal's secret crush, has any idea that Mal is anything more than a dork. Fortunately, Mal and Chad are best friends with a penchant for adventure . . . even if the time-traveling does get them grounded by Mal's mom.