Providing instruction on spatial geometry, specifically how to calculate the surface areas of composite solids, challenges many elementary school teachers. Determining the surface areas of composite solids involves complex calculations and advanced spatial concepts. The goals of this study were to build on students' learning processes for basic and composite solids and employ Google SketchUp, an Internet resource tool, to develop and implement surface-area instructional and learning strategies (SAILS) for composite solids, and then measure its effect on learning achievement and attitudes. The fifth-grade students ("N" = 111) who were enrolled in this study were divided into an experimental and a control group. The experimental group ("N" = 56) received SAILS instruction, whereas the control group ("N" = 55) received traditional instruction. The results indicated that students who received SAILS instruction exhibited better performance on both immediate and maintained surface-area learning achievement tests compared to those who received traditional instruction; furthermore, this effect was more prominent among boys than girls. Low- and moderate-ability students who received SAILS instruction exhibited significantly greater improvement of attitudes toward learning mathematics compared to those receiving traditional instruction with physical teaching aids.