Biogeochemical cycles

2. History of Rock

Every rock holds clues about how it formed. Geologists are like rock detectives who know how to read the clues about a rock’s origins and the stories it can tell. In this activity, students first become specialists in one type of rock. Then, they meet specialists in other rock types to compare their rocks and teach the others about their rock’s history. This lesson is an opportunity for students to consolidate information from the previous lesson on the rock cycle, and begin to think like geologists. Ideally, the rocks selected for investigation are collected from the site of an upcoming geology field trip – such as to the Caldecott Tunnel or Mount Diablo. In this way, students gain experience identifying individual rocks and learning about the way in which each of the different rock types form. Then, on the field trip, students can apply their controlled classroom knowledge to real world geological history.

1. Crayon Rock Cycle

What's the big deal about rocks? They don' move, aren't flashy, and seem pretty useless to the untrained eye. To discover the beauty of rocks, one must look closer and learn how to read them. Geologists are rock detectives, discovering clues to the ancient past. If you know how to read them, rocks can tell an observant scientist about what a place looked like millions and even billions of years ago. This activity introduces the 3 main types of rocks and the processes that form them. Wax crayons are eroded into sediment, compacted into sedimentary rock, partially melted and pressed into metamorphic rock, and finally melted and cooled into igneous rock. This understanding is the basis of the rock cycle. In the Going Further section, there is a recipe for making your own sandstone, siltstone and conglomerate using sediments and a sodium silicate solution.

Can describe the 3 major types of rock (sedimentary, metamorphic, and igneous) and discuss the relationships between them
Can diagram the rock cycle
Given one of the three major types of rock, can describe the geologic processes that formed it

1. Water Cycle Stories

In this lesson, students review the water cycle (a concept most have hopefully explored before in elementary school science) and write stories to describe the journey of a water molecule through the water cycle. They begin by labeling a drawing of the water cycle, noting the locations that water may be stored on the planet and the processes through which water travels from one location to another. They then envision several journeys as a class before writing a story to describe the journey of a water molecule through the water cycle. An optional mini-investigation to complement this lesson involves observing the transition of water through its 3 phases (ice, water, water vapor) after an ice cube is zipped into a resealable plastic bag and taped to a sunny window.

2. Water Analysis


Students conduct 3 tests of water quality in the classroom that can then be applied to their terraqua columns and to the outdoors: pH, dissolved oxygen, and temperature. They make comparisons between different types of water and draw conclusions about how "healthy" each water source is for fish and other organisms. Through this process, students practice their observational and data analysis skills. Water quality monitoring data is routinely used in the "real world" to determine the effects of habitat restoration, development, pollution, and wastewater treatment. It is often the initial step in describing the health of an ecosystem. There are hundreds of ways to extend this simple activity and make connections to the real world - from monitoring water quality in a local creek to making comparisons between different bodies of water in your area.