This study aims to cement the link between systems thinking (ST) and education for sustainability by presenting an example of systems education for young children. A systems education guidebook focused on water and a learning framework based on the guidebook were developed, together with two ST assessment instruments (a shared reading and a concept mapping activity with interview protocols). The learning framework was implemented over the course of four-weeks with 32 children aged 5-6 in a pre-school in Turkey. To measure the outcomes, the children were pre-tested and post-tested with the assessment instruments using a mixed method approach. The results revealed a significant development in the ST skills of the children. Children defined system elements related to water more, came to see invisible elements as parts of the system and established high-quality causal relations between system elements related to water.