This article describes constructivist techniques for teaching concepts of decimals and metrics through the combination of innovative measuring tools, activities and videos in classrooms. Even though the chronological age of the students involved differed--fifth and sixth graders or pre-service teachers--it was discovered that similar activities helped all students learn the decimal and metric systems. Through teacher observation and informal interviews made by the authors, recommendations are made to upper-elementary math and science teachers as well as mathematics and science methods teachers at the university level. (Author/WRM)