Within the curriculum guidelines for Bavaria, we designed a hands-on educational programme for teaching sustainability with regard to agriculture, food and consumerism, partly implemented on a farm as an out-of-school learning setting. The participants were fifth graders ("N"?=?176). The research followed a quasi-experimental design and used the subscale "consumerism" of the "General Ecological Behaviour Scale" and situational emotions (interest, well-being, boredom) to focus data collection activities. The study monitored the students' knowledge increase and their "Inclusion of Nature in Self" (INS) scores as possible influencing factors on environmental behaviour. After participation in the programme, while we found that the students intended to consume in more environmentally friendlier ways, this intention did not persistent over a seven-week time span, nor did it relate to the INS or knowledge scores. There was, however, a high correlation with positive situational emotions like "interest" ("r"?=?0.46, p =?0.001) and "well-being" ("r"?=?0.39, p?=?0.001), and a negative correlation with "boredom" ("r"?=?-0.42, p?=?0.001). We conclude that the "effect" of the programme immediately measured after the intervention was strongly linked to situational (short-term) emotions, and should be considered in educational planning as well as the evaluation of sustainability teaching and learning.