Course: Intro to Agriscience Unit: Ag Mechanics Lesson: Surveying Situation: 9th and 10th grade students with little to no knowledge of surveying equipment. 1st Interest Approach: Set up a scenario where water is not draining from your yard or a certain place. Ask questions why the water isn’t draining away from the area to gain responses from the class. Then tell them that with the use of surveying, we can figure that the two ends of the water problem are at different elevations causing the water to sit in one place. 2nd Interest Approach: Bring in a surveying setup and review the parts of a level to bring up the next section of class. 3rd Interest Approach: Review how to shoot grade and use a level, and then proceed to move to using the level in a lab. Objectives 1. Define different terms involved in surveying in the classroom with 100% accuracy. 2. Identify different parts of a level on a worksheet with 100% accuracy. 3. Demonstrate how to successfully set up a tripod used in surveying in a lab with 100% accuracy. 4. Demonstrate how to successfully adjust a level in a lab with 100% accuracy. 5. Demonstrate how to find slope with a level in a lab with 100% accuracy. 6. Apply knowledge of surveying to find slope between two points in a lab with 100% accuracy. Reasons to Learn 1. Why do we need to know about surveying? 2. Why do we need to know the different parts of a level? 3. Why do we need to know how to set up and adjust a level? 4. Why do we need to learn how to shoot slope between two points? Answers to Reasons to Learn 1. So we can determine our property boundaries, so we can level things in construction, or so we can determine elevation to hold or drain water on our property. 2. So we can know what to adjust when I tell you to adjust something. We can also know what to inspect or replace if we know the parts. 3. Without knowing how to set up and adjust a level, we would not be able to survey. Also, learning how to set up a level enables you to set one up on your own. 4. So we can know how to keep our buildings or how our water drains, among other things. Transition: Now that we know why we need to learn, what are some questions we need to ask about surveying? Questions to Answer 1. What is surveying? 2. What are the parts of a level? 3. How do we set up and adjust a level? 4. How do we shoot slope between two points? Key Terms Backsight Reading- A reading taken on a point of known elevation. Benchmark- A point of predetermined elevation. Clamp Screw- Locks the instrument in position so that it cannot be turned off the target. Elevation- The height of a point relative to the benchmark location of the survey. Fine Adjusting Screw- Makes fine adjustments to the left or right. Foresight Reading- A reading taken on a point of unknown elevation. Height of Instrument- Backsight plus elevation. Level- Instrument used for measuring vertical distances over large horizontal areas. Leveling Base- Holds four leveling screws for leveling the instrument prior to use. Pacing- Estimating the length of a line by counting the number of steps taken along the line. Protractor- Scale graduated in degrees and minutes, or 1/60 of a degree, used for measuring horizontal angles. Slope- different between two points, such as your backsight and foresight. Target (Surveying) Rod- A pole-like device with a scale graduated in feet and tenths of a foot. Telescope- Contains the lens, focusing adjustment, and crosshairs for sighting. Telescope Level- A spirit level used for leveling the instrument when it is set up for use. Tripod- Three-legged stand that provides a stable, yet portable, base for the instrument. Materials Level Tripod Target Rod Pencil Paper Calculator Discussion What is surveying? a. The measurement of dimensional relationships, as of horizontal distances, elevations, directions, and angles, on the earth's surface especially for use in locating property boundaries, construction layout, and mapmaking. b. Basically, surveying is used to find out where your land ends and your neighbors starts, or how elevated a piece of ground is. c. Surveying is commonly used in construction to pour footings, or foundations. Surveying shows how deep you have to dig your foundation to keep your house level when you build it. It is also used to determine your lateral lines or water pipes to make sure they are lower than the source. d. Problems arise when you don’t know when your property ends and your neighbor’s starts. When you want to sell your land you have to have a deed drawn up that shows where your property is. To know your exact boundaries, you have to hire a surveyor to come in and survey your land. Most of these guys have electronic GPS stations to prevent them from having to set up equipment like we will in this unit. However, they still have to walk through woods and up hills flagging and marking to show boundaries. Parts of a Level The picture below shows the parts of a level. Keep in mind that not all levels are the same and they differ with different brands, but typically all levels have this general setup. 1.Telescope level 2. Telescope focusing knob 3. Telescope 4. Clamp Screw Locks 5. Fine Adjusting Screws 6. Protractor 7. Leveling Screws 8. Leveling Base Surveying Rod The Art of Pacing a. Pacing is the art of judging distances by the amount of steps you take to get from your point of origin, to your destination. Basically, how many steps do I need to take to get to the spot I want to go. b. The hardest thing about pacing is keeping your numbers consistent. A step on a flat field will be a different length than a step going up a mountain covered in briars. A surveyors tape can be used, but it is commonly used by two people, and in some situations is very impractical. You can also use a foot ticker that involves a wheel and a ticker that measures off feet. But again, in some terrain it isn’t practical. c. To figure out your pacing steps distance, the best way to practice that is to measure out a certain distance, and step it off several times. Divide your distance by however many steps you take, and that gives you how many feet per step you take when you pace. It’s not the most accurate way of judging distances, but when you are in a pinch it helps pretty well. How to Read a Surveying Rod (Target Rod) a. The large red numbers are your feet, and the black numbers between them are the tenths of a foot. b. The bottom of the black lines are odd hundreths. The top of the black lines are even hundreths. c. Top of line at the red number is exactly a whole foot, and the tops of the lines at the tenths are exactly a tenth of a foot. How to Read a Level a. The first step to surveying is to have all your equipment handy. Make sure you have your tripod, your level, and your surveying rod. Also, have paper, pencil, and a calculator handy to figure your calculations. b. Observe the safety rules involved with surveying. 1. When transporting the level, protect it from shock and vibration. 2. Never run with the transit. 3. Pay attention to walkways and surroundings. 4. Clean and put away equipment after using. 5. Report any broken equipment to me. c. Here are the steps to setting up a level. 1. Set your level up on a convenient place to where you can see both your foresight and your backsight readings. 2. Set level on top of your tripod, and hand tighten the screw clamp. 3. Turn the leveling screws down so that they contact the tripod plate. 4. Turn the telescope so that it is over one pair of leveling screws. Adjust these two screws to make the telescope level. 5. Turn the telescope so that it is over the other pair of leveling screws. Adjust these two screws to make the instrument level. 6. Repeat steps 4 and 5, alternating over both pairs of leveling screws until the instrument is level in both positions. Be careful not to touch the tripod with your foot. The slightest jar of the tripod will cause the instrument to be knocked out of level. 7. Have a partner hold the target rod over your benchmark, or the place you know the elevation, while you sight through the telescope and focus the crosshairs on the target rod. This is what we call our backsight. Write down the measurement seen through the telescope. 8. Whatever reading you get on your rod, subtract that number from your known elevation. This is called your height of instrument. 9. Have your partner move the target rod to the other spot of unknown elevation. Carefully rotate the instrument, without touching the tripod, so that you can focus on the target rod at this location. Take your reading on your level, and write it down. This is called your foresight. 10. To get your slope, or whether it rose or fell from one point to the other, subtract the smaller reading from the larger one to find the difference in elevation, or your slope, from one point to the other. Lab Activity Have the kids break up into however many groups that can have their own surveying level. Give them their equipment, and have them set it up. Have the students set up their level, and shoot several different locations so they can get practice in how to find the slope or elevation change. When they finish the worksheet on what they are shooting have them turn the worksheet in. Make sure to go through how to set it up once before you turn them loose on working. Summary Briefly… a. Go over the terms. b. Go over what surveying is. c. Go over the parts of a level. d. Go over pacing. e. Go over how to read a rod. f. Go over how to set up a level. g. Go over how to use a level. Evaluation Hand out the exam on the final day. Use a variation of the surveying test that follows the frameworks on the Arkansas FFA website.
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