John Allison 
Bad Machinery Vol. 1: The Case of the Team Spirit [PDF ebook] 

Shauna. Charlotte. Mildred. Three schoolgirl sleuths. Jack. Linton. Sonny. Three schoolboy investigators. Tackleford. One mid-sized city with a history of countless mysteries. Is there enough room at Griswalds Grammar School for two groups of kid detectives? There better be, because once these kids have set their sights on solving a mystery there’s nothing that can derail them. Nothing, except maybe gossip, classwork, new football player cards, torment from siblings, or any number of childhood distractions.