The aim of this study is to conduct Arts and Crafts classes aiming at fostering '21st century skills' by using soil-clay which is not frequently used in Arts and Crafts class at elementary schools, and to investigate its effect on 21st century skills among pupils. Participants of this study were second-grade elementary school pupils. They participated in a cooperative production using soil-clay. Then, effects of it on pupils' 'basic skills, abilities to think, and abilities to practice in 21st century skills' were examined through observation of pupils' activities and questionnaire. As a result, the class was proved to be effective. After the experimental classes, pupils' positive answers were increased on skills such as 'basic ability', creativity as 'the ability to think', cooperativeness as 'the ability to practice'. Therefore, the class needs further improvement solve problems of how teachers would identify and foster children's 'individual expression', which tends to be hidden under cooperative production.