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Second Grade – Lesson Overview Pebbles, Sand, and Silt Students Learn: Rocks have a variety of properties. When rocks rub together, some (softer) rocks may be chipped or scratched, or make rock dust. Rocks have a variety of properties. When rocks are washed in water, the colors or sparkling qualities are enhanced. Rocks can be sorted by their properties. Investigations: Investigation 1, Part 1: Three Rocks Students Do: Students investigate and sort a set of six rocks. They gather information about the rocks by matching the rock samples and rubbing them together. Investigation 1, Students wash their samples to see Part 2: how the rocks change when they Washing Three are wet and what happens to the Rocks wash water. Investigation 1, Students are introduced to river Part 3: First rocks. They listen to the story Sorting “Peter and the Rocks” and use ideas from the story and Part 2 to sort their river rocks. Rocks can be sorted by their Investigation 1, Students use sorting mats to play properties. Part 4: Sorting sorting games with the river rocks. games. Rocks are all around us. Rocks Investigation1, Students start to organize a are the solid material of the Part 5: Start a classroom rock collection. Earth. Rock Collection Screens can be used to sort the Investigation 2, Students separate a river rock sizes of earth materials. Rock Part 1: mixture, using a set of three sizes include sand, small Screening River screens. At the end of the gravel, large gravel, small Rocks. separation, students discover they pebbles, and large pebbles. have five sizes of materials: large pebbles, small pebbles, large gravel, small gravel, and sand. Rocks can be categorized Investigation 2, Students activities reinforce the visually by size. Rock sizes Part 2: River idea of grouping rocks based on include sand, small gravel, Rocks by Size size. large gravel, small pebbles, and large pebbles. Rocks larger than pebbles are cobbles. Rocks larger than cobbles are boulders. Sand often contains smaller Investigation 2, Students take a close look at sand particles, called silt. Water Part 3: Sand and separate sand particles from can be used to sort the sizes of and Silt silt particles, which are smaller earth materials. than sand, by mixing the sand with water and allowing the particles to Clay particles are very small, even smaller than silt. Earth materials are natural resources. The properties of different earth materials make each suitable for specific uses. Earth materials are commonly used in the construction of buildings and streets. The properties of different earth materials make each suitable for specific uses. The properties of different earth materials make each suitable for specific uses. Earth materials are used to make jewelry and sculptures. The properties of different earth materials make each suitable for specific uses. The properties of different earth materials make each suitable for specific uses. Simple bricks are made by combining clay soil with plant material. Soil is a mixture of earth materials. Humus is decayed material from plants and animals. The ingredients of soil can be observed by mixing soil with water, shaking it, and letting it settle. Soils vary from place to place. settle. They observe that the sand settles to the bottom and the silt forms a layer on top of the sand. Investigation 2, Students investigate the properties Part 4: of very small rock particles, clay. Exploring Clay Investigation 3, Students learn how people use Part 1: Rocks rocks as natural resources to and Use construct objects and to make useful materials. They start by looking outside the school building for places where earth materials can be found naturally or as building materials. Investigation 3, Students observe sandpaper and Part 2: Looking compare it to sand. They make at Sandpaper and compare rubbings of three grades of sandpaper. Investigation 3, Students mix sand with cornstarch Part 3: Sand matrix to make durable sand Sculptures sculptures. Investigation 3, Students use clay to make beads or Part 4: Clay something decorative, which they Beads paint and keep as a memento of their investigation of clay. Investigation 3, Students make adobe clay bricks Part 5: Making with a mixture of clay soil, dry Bricks grass or weeds, and water. After the bricks dry, the can be used to build a class wall. Investigation 4, Students put together and take Part 1: apart soils. They are introduced to Homemade Soil humus, an important soil ingredient. They mix together homemade soil containing sand, gravel, pebbles, and humus. They shake some of the soil on a paper plate and observe what happens. They use screens to separate the homemade soil. They shake soil and water together in a vial and draw their observations. Investigation 4, Students go on a schoolyard field Soils have properties of color and texture. Different soils differ in their ability to support plants. Soils can be composed of humus and different amounts and sizes of rocks. Part 2: Soil Search trip to collect soil samples. They try to find soil in as many places as possible: next to sidewalks, near trees, and in landscaped area. Investigation 4, Students study their schoolyard soil Part 3: samples. They shake some of the Studying Local soil with water in vials and draw Soil the results. They compare the vials in drawings of their schoolyard samples with the vials and drawings of the homemade soil.