Title of Lesson. Understanding Sand

Transcription

1 Title of Lesson Subject Area Age or Grade Level Understanding Sand A lab designed to teach students what sand is from a physical classification standpoint and how sand can differ from beach to beach. 7 th grade This lab is designed as an introduction to the idea that sand is actually a geology size classification, and the term sand itself only denotes particles between 1/16mm and 2mm in size. Ideally within this lab, the class will have collected sand from various beaches (the more the better) and the observation (via microscope) along with some rudimentary chemical reactions (Calcium Carbinate with vinegar) to help distinguish between various sand protoliths. This topic is especially relevant for schools near water (such as Quincy) and can be easily transitioned into a lab or discussion about beach erosion from a physical and chemical perspective. I believe this lab is a great way to start an overall environmental science unit. Brief Overview Basic classification of sand requires a microscope and different types of sand. Students will sort out types of sand via 2 qualitative characteristic (angularity and morphology), 2 quantitative characteristics (sorting percentage and specific grain sizes) and one chemical reaction (acid-base reaction). The chemical reaction component can be be as expansive as using HCl (not recommended for a middle school setting) or easy as using vinegar. Ideally, one of the sand samples should be calcium carbonate sands, but that might be hard to obtain in certain locations. As a substitution, we can use TUMS (or another easily obtainable calcium carbonate based medicine) which has been crushed into small pieces. The vinegar (an acid) should react with the CaCO3/TUMS (a base) and fizz with many bubbles. This is indicative of a release of CO2 gas. See Attached documents for a methodology of lab experiment, examples of different types of sand worldwide, and analysis questions. Estimated Time This lab will work best as two classroom days. The first day will consist only of analysis of sand samples. Day two can be dedicated to analysis of the different types of sands and the

2 various observations made from different sand types. Standards/Unit Goals Students will be able to determine differences between types of sand and understand how the properties of sand can be connected to beach erosion and weathering. 1) What is sand (from a physical perspective) 2) Where does sand come from, and how can this vary? (Introduce vocabulary word: Protolith ) 3) What can sand tell us about it s protolith and local environment/geology? Essential Questions 4) What are the different ways to differentiate between sand? 5) Why do you think some sands reacted with the vinegar and some did not? 6) Why is sand type important to beach erosion? 7) How can different types of sand erode as different rates? Skill Objective(s) By end of this lesson, students will be able to Understand the concept of sand and it s effect of beach erosion and protolith environment. Knowledge Objective(s) By end of this lesson, students will know - Understand the variations in sand types - Microscope skills and measurements made under a microscope. - Microscope (40x ideal, but whatever is available will work) Materials Needed - Various types of sand. At the very least twodistinct locations but the more the merrier. - Calcium Carbonate sand. If none is available, substitute crushed up TUMS. - Rulers (with mm measurements) - Vinegar Technology Tools Used Useful Vocabulary New Vocabulary Word 1 Microscope. Acid (vinegar is ideal).protolith, Grain Size, Angularity, Grain Size Sorting Prerequisite knowledge/skills Knowledge of the rock cycle. How weathering and erosion occurs (but not to a great extent)

3 Anticipated Student Preconceptions/Misconceptions Students have probably only been exposed to sand as part of a beach. This lab is designed to introduce the idea of sand as a size classification. As such, different sized clasts might be useful to show the difference in grain sizes. In order to determine the sorting of the sands, students will have to isolate ~100 grains. This might be hard and/or tedious for certain kids. Be sure to keep them on task! Instructional Tips/Strategies for the Teacher Opener. Introduce the lab and have students review the lab procedures. Introduce the concept of sand as a size classification. Have students list and talk about where they have seen sand or been exposed to it (before and after defining the size classification) Lab. Students should split up into groups of 2-6 (depending on availability of microscopes and number of sand samples). Have each group determine the average size of the sand grains (using a mm ruler) and average angularity of the sand particles. Lesson Sequence Each lab group should separate ~100 grains of sand and then calculate the sorting of the sand. (i.e. well sorted to poorly sorted). In each group there should be a designated recorder along with 2 or 3 counters. Roles should remain the same through the course of the lab. Once the above activities are done, it is time to test the chemical reactions within the samples. Take the vinegar and drop onto the various sand samples. When the vinegar touches the calium carbonate sand (or TUMS) it should start to fizz. Have the students brain storm why that may be happening. Closure: Lead a discussion on the various types of sand the students have observed. As a class talk about the variations in grain size and sorting, along with angularity of different samples. Resources Weblinks Reproducible Materials This portion should lead to an overall discussion on beach erosion and weathering. Ask students how different types of sands might be eroded differently than other types of sand they have observed. Introduce the idea of ocean acidification. Could a higher ph (like vinegar) affect beachs made out of CaCO3? See attached pdfs below

4 References Assessment Students should conduct a small report (or homework assignment) on the different sands seen around the globe and from personal experience. Extensions/Explorations Reflections Contact Information

5 Understanding Sand - Lab Activity Materials & Procedures Materials and Equipment Required: - Microscope (40x ideal, but whatever is available will work) - Various types of sand. At the very least two distinct locations but the more the merrier. - Calcium Carbonate sand. If none is available, substitute crushed up TUMS or antacid. - Rulers (with mm measurements) - Vinegar (or some other type of acid) Procedures. 1. Carefully set- up microscopes and associated slides or dishes to be analyzed 2. Prepare samples of sand for microscope a. This can include putting a small amount of sand on a slide or on a larger glass dish (whichever fits on the microscope stand) 3. Designate roles within the lab group a. 1 Recorder b. 2-4 Observers c. 1 Measurer (in charge of size measurements and grain size calculations) 4. Carefully place sand samples underneath the microscope. a. Make initial observations of sand underneath the microscope. b. Describe in lab notebook some qualitative (non- technical) characteristics c. Observations can include: i. Colors, Shapes, Sizes, Opacity, etc 5. As a group determine the overall angularity and sphericity of the sand grains a. Use given chart to make this determination. Remember, this is an average angularity and sphericity of the entire sample. Use the terminology shown in the chart b. You will see different angularities and sphericities within the sample. As a group you must come to a consensus. This will require team-work and repeated observations. c. Write down the justification for your lab group s choice in your lab notebook.

6 6. As a group determine the range of sand grain sizes in your sample. a. Have one person be the designated measurer, but have the rest of the group check the work and make his or her own observations. 7. Select ~50 grains from your sand sample a. Determine an average grain size for your sample b. Determine the sorting of the sand sample. i. Refer to chart below. ii. Show the percentage of large/medium/small grains before defining the final grain sorting classification. iii. Remember, sorting refers to the variation in grain sizes within your sample. c. In your lab notebooks write a sentence on how human bias could affect grain- sorting classifications. 8. Collect a Calcium Carbonate Sand sample (might be crushed up antacids) from the teacher a. Quickly calculate the grain sizes, angularity/sphericity, and overall grain- sorting of this new sample. 9. Drop a teaspoon of vinegar on your orignal sand sample and on your new carbonate sand sample a. In your lab notebook describe what happens in each instance b. What do you think is happening with the carbonate sand? c. Why do you think something different happening in your original sand sample 10. Clean up sand from your work area. Prepare and clean microscopes for the next class.

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9 Some Common (and Uncommon) Examples of Sand

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