Written by Alyssa Burley.
Over two days (May 5th and 12th) Project Cornerstone's Alyssa Burley and Crystal Howard, EnviroMINE's James DeCarolis, and volunteer Barbara took turns visiting five fifth-grade classes at Central Elementary in San Diego, CA. Students learned about the importance of construction aggregates (i.e., sand, gravel and crushed stone).
After a short presentation, students were asked to look at two samples of construction aggregates (one with river sand and one with beach sand) and develop a hypothesis for the sample they thought would be best suited for making concrete. The students tested their hypothesis by performing a sieve analysis. The sieve analysis allows the students to separate the materials by size using a series of screens. The students weighed the contents captured on each screen. The sample with the least amount of very fine sand is best for making concrete. As expected, the students found river sand to be best for making concrete.
Using information learned during the presentation, students mixed their own concrete being careful to follow the recipe in order to keep the correct portions of sand, crushed stone, recycled aggregate, cement and water.
The presentation, sieve analysis and concrete project are designed to support the Next Generation Science Standards.