Adding Mentos to an open bottle of Diet Coke can produce a fountain of liquid and froth extending several metres high. This activity can engage a wide audience of learners in a relevant and meaningful way, provide a model for creative science teaching, and help to develop learners' attitudes towards school science as a subject. In this paper, the authors describe the use of this activity with primary-aged learners. Some challenges associated with the construction of the delivery mechanism for the Mentos are discussed, and ideas are provided for improving the performance of the fountain. An activity that provides an unexpected or startling outcome is usually guaranteed to generate interest, excitement, and enthusiasm from learners of any age. Teachers often look to activities that not only inspire learners but also develop curiosity. The Mentos and Diet Coke activity is one such activity that has been made much more accessible to a wider audience through the Mythbusters television programme (Savage & Hyneman, 2006) and the science educator Steve Spangler (Steve Spangler Science, 2010a). Fritz Grobe and Stephen Voltz, the creators of EepyBird, have taken the Mentos and Diet Coke activity and developed new and unusual ways of presenting the activity through performance art, and their 2006 video, "The Extreme Diet Coke & Mentos Experiments" (EepyBird.com, n.d.), has been watched by millions. The popularity of the Mentos and Diet Coke activity has led to thousands of creative home videos being uploaded onto YouTube. The Mentos and Diet Coke activity has been successfully used by teachers to demonstrate science processes involved in completing an open-ended physics experiment with undergraduate physics students (Coffey, 2008b). The primary goal was to engage the physics students in "real" research. The students worked collaboratively to explore the different aspects of the activity, including the type of sweets used, temperature of the soda, and ingredients in the sweets and soda. The results from the work of these undergraduates were then published in Coffey (2008a). The interest in the Mentos and Coke activity resulted in the students' findings being reported in the popular science magazine "New Scientist" (Muir, 2008). This activity has also been used within undergraduate Chemistry courses to create curiosity and engagement with an authentic science focus (Baur, Baur, & Franz, 2006; De Grys, 2007; Eichler, Patrick, Harmon, & Coonce, 2007; Liljeholm, 2009; McGuyer, Broen, & Dang, 2009) and also as a model for volcanology investigations (Quane, Klos, & Jacobsen, 2009; Wright, Rust, & Cashman, 2006). Howarth and Woollhead (2008) described the use of this activity with younger learners (12- and 13-year-olds) as they modelled the volcano effect during a class on earth science. (Contains 1 figure.)