Geometry ability and spatial estimation ability are perceived as important abilities that humans should learn. However, current geometry teaching at elementary schools mostly focuses on calculation process with the traditional approaches such as paper, pencils and rulers, but rarely connects geometry learning to students' real life. So we developed a Ubiquitous Geometry (UG) system to support ubiquitous geometry learning in real situation. This study explored whether ubiquitous geometry learning in real situation can improve geometry learning, especially deeply investigating learning behaviors using the UG system and their effects to learning. After a quasi-experiment, the results showed that the users had high learning motivation and intention to use the UG system. Furthermore, it was found that geometry learning performance and spatial estimation ability of the experimental group were significantly higher than those of the two control groups. Further analysis found that the participants who had measured more real objects had better learning performance. Hence, the UG system and learning activities in this study provided a good approach to enrich applying geometry to real life and had good effects on geometry learning. Based on the results of the study, we give some advice on the design of teaching activities and teaching methods.