Project Cornerstone Visits 5th & 6th Graders at Rohr Elementary

Written by Alyssa Burley.

On January 20th, 2016, Project Cornerstone visited with 56 students at Rohr Elementary School in Chula Vista, CA.

The 5th and 6th grade students from Ms. Gurrero's and Mr. Talbot's classes participated in Project Cornerstone's lesson on construction aggregates (i.e., sand, gravel and crushed stone) used in building materials like concrete and asphalt products.

The two classes learned how construction aggregates are used to build homes, roads, bridges, schools, etc. in the community, and where the materials are naturally found throughout the county.


Each student developed a hypothesis for which type of sand (i.e., river or beach) they thought was best for making concrete based on what they learned in the lecture and their own observation.  Then, in small groups, the students used a sieve and scale to analyze the two sand samples.  Looking at the data collected, the students determined river sand is best from making concrete.

After completing the sieve analysis, one student excitedly said, "I want to do this everyday!"  Another student said with a giant grin on her face, "Yay! We did this last year."


Students then made their own concrete using the correct proportions of sand, gravel, cement and water.  They witnessed first-hand the hydration process which transforms the liquid concrete mixture into a solid building material.

Photos by Alyssa Burley

Rohr Elementary Students Learn About Local Construction Aggregates

Written by Alyssa Burley.

Project Cornerstone's Alyssa Burley and EnviroMINE's James DeCarolis visited two sixth grade classes at Rohr Elementary in Chula Vista on May 8, 2015.  

The sixth-grade students learned about the role construction aggregates play in their daily lives.  They also learned where the materials are mined locally in their community.

The students broke into six groups of about five students and performed a sieve analysis.  The sieve analysis requires the students to test two aggregate samples to see which one is best suited for making concrete.  The sample is poured into the sieve (a cylinder with a series of screens with varying size holes).  As the students shake the sieve, the material is separated by size.  One sample had river sand while the other had beach sand.  As expected, the students determined river sand is best suited for making concrete because it has the smallest percentage of very fine sand. 

Students also made their own batches of concrete using sand, gravel, cement and water.  Using silicone molds, the students were able to pour their concrete into various shapes like jeeps, trucks, butterflies, ladybugs, footballs and more!

The presentation, sieve analysis and concrete project are designed to support the Next Generation Science Standards.


Sixth-grade students at Rohr Elementary performing the sieve analysis and a complete concrete project (football).