This study investigated meaning-making of arrows in a representation of the greenhouse effect among 14-year-old secondary school students. Data was generated during Biology lessons where 74 students discussed how they interpreted a representation from the Swedish Society for Nature Conservation, which is an NGO that produce school material. The students were divided into 33 groups, who made written notes. In addition 12 groups were videotaped and eleven of these groups were interviewed a week later. The analysis focused on meaning-making of the arrows in the representation with the starting point that the arrows were represented in two distinctive ways, colour (yellow/orange) and shape (straight/curved/wavy). The result show that the colour yellow was strongly connected to the Sun whereas orange was connected to heat. The mode waviness made meaning-making more diverse and the coupling to the colour orange triggered interpretations about heat and different emissions and gases. One implication is that arrows are interpreted in the light of everyday experiences. In order to make sense in a more scientific way the arrows need unpacking and contextualisation. The overall connection between meaning-making and representation was captured by one group as: "It is an easy representation, if you understand it".