OUR TRIBE

Meet The Team Behind Challenge Island

Sharon Duke Estroff M.A.T.

Founder & CEO

Sharon is founder and creator of the Challenge Island™ program, She is an award-winning elementary school teacher with two decades of experience in Atlanta public and private schools. She started Challenge Island in her second grade classroom and began running it as an enrichment business using the current model in 2003. It has been growing by leaps and bounds ever since.

Sharon is a nationally recognized parenting and education expert and a freelance writer for numerous national publications including Scholastic Parent and Child, Parents, Woman’s Day and Good Housekeeping magazines. She is the author of the popular parenting book, Can I Have a Cell Phone for Hanukkah? (Random House) and co-author of the upcoming Challenge Island book series that turns the Challenge Island curriculum into an exciting and educational story. She is sought-after speaker who has presented to scores of communities nationwide about the trials and tribulations of raising kids in the digital age.
Sharon received her undergraduate and graduate degrees from Emory University where she graduated Phi Beta Kappa and Summa Cum Laude.

She continues to run her local Challenge Island business in Atlanta, Georgia where she lives with her husband and four children.


JoAnn Mannarino

Owner – Challenge-Island Southwest Orlando

JoAnn received her Bachelor of Arts degree in Speech Communications from West Chester University, West Chester Pennsylvania.  The mother of two children, JoAnn has been an Orange County Public School Volunteer since 1990, volunteering both in the classroom as well as other school events.

Prior to raising children, JoAnn had a career in Sales and Marketing.  Her strong communication skills, creativity and love of children and learning led her to her passion as a Challenge Island Owner.  JoAnn resides in Windermere, Florida.

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