## Peak Performance

Name of Activity Peak Performance Jay Clark NXT, car, course, fastest, flat, inclined, gear, gear ratios, torque, speed, optimization, building, drive gear, driven gear, 1 Hour Total NXTs K, 1, 2, 3, 4, 5, 6, 7, 8, 9+ 1 Hour Total Students must gear their NXT car to complete the course the fastest. The course consists of a flat section and an inclined section. To learn about gear ratios, gearing for torque vs gearing for speed, optimization, and building. NXT kit Ramp Computers running MINDSTORMS Prepare one or more courses – With a flat beginning and an incline ending. The length of both sections will determine the optimum gear ratio. To allow for extensions, set up other courses with varying distances of the course components. Using gear ratios students can gear their cars for more torque or more speed. If the drive gear is bigger than the driven gear, the car will be geared for speed. If the other way around, it will be geared for torque. A car geared for torque will be slower, but will climb better. A car geared for speed will be quick, but might not be able to climb the ramp. Vocabulary: Gear Ratio – The ratio of the speed of rotation of the drive gear of a gear train to that of the driven gear. Drive Gear- The gear attached to the source of torque. (Usually the motor). Driven Gear – The gear that receives motion from the drive gear. Optimization – Finding a balance between design concerns that yields the best solution. Introduction – 10 Minutes Ask students if they’ve ever used gears before. More than likely, they’ve driven a 10 speed bike before, and never knew how the gears worked. Introduce students to gears and gear ratios. Using a pre-made gear train, show them the size of the drive gear and the driven gear, and ask if the driven gear will spin faster or slower than the drive. If they are having trouble seeing it, ask them for every one rotation of the drive gear, how many times does the driven gear rotate? Explain torque vs. speed. ie. tugboats – high torque, low speed. Handheld fans- high speed, low torque. Introduce the concept of optimization. Introduce the activity Activity – 40 minutes Clean up/ Wrap up – 10 minutes What was easiest? What was hardest?  What would you have done differently?  What were some good ideas you saw that other groups came up with? Have the students try a different course with different dimensions and slopes. http://sites.tufts.edu/stompactivitydatabase/files/formidable/e.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/f.jpg

## Tug-O-War

Name of Activity Tug-O-War Kara Miranda gear, gear ratios, build, machine, tug-o-war, competition, prototype, Engineering Design Process, torque NXTs 4, 5, 6, 7, 8, 9+ 3 Hours Total Students will use their knowledge about gears and gear ratios to build a machine that will play tug-o-war against another classmate’s. To apply building techniques and knowledge about gears to an activity challenge. RCX or NXT LEGO kits Assortment of extra LEGO pieces, especially gears and beams Engineer’s Planning Sheet String Scissors Tape Collect necessary materials Photocopy worksheets Arrange students into groups of 2 Decide how you will distribute extra pieces Write design requirements on the board Review gears, gear ratios, and torque. Vocabulary: Prototype Engineering Design Process Gears Gear ratio Torque Tell students that in this challenge they will be playing tug-o-war by building a machine that can provide enough torque to pull on another machine doing the same thing. String will be tied between the two, and a machine will have to pull the other over a line of tape in order to win. Make sure to review how gears work, gear ratios, and using gears for torque vs. speed. Also explain the engineering design process. Tell students the requirements for their tug-o-war contenders. Examples of requirements are:       Must use gears       Must have a sensor Allow the class to brainstorm different ideas for their machines. Have them plan out and draw their design on the engineering planning sheet. Distribute materials and have students start building. You may have to assist students with tying string to their machine. After the students finish building, pair up machines and tie them to either end of a string, making sure the middle of the string is right above the tape on the ground, and that both machines are equidistant from the tape. Have the students start their machines. Whoever’s machine gets pulled over the line first, loses. After the students finish, review the activity with the class. Have them share their ideas, ask groups to explain what the hardest part of the challenge was, etc. Have students add more gears Make a classwide tug-o-war competition. Whose is the “strongest”? Allow those who lose to redesign and compete against each other again http://sites.tufts.edu/stompactivitydatabase/files/formidable/a.pdf

## Spin Art

Name of Activity Spin Art Kara Miranda open-ended, design, challenge, design, build, spin, create, art, markers, crayons, paint, art supplies, not classroom tested, NXT, toys, prototype, Engineering Design Process, Gears, gear ratios, 4-6, 7-9, 2 Hours Total NXTs 4, 5, 6, 7, 8, 9+ 2 Hours Total An open-ended design challenge in which students will design and build an object that will spin in some manner to create art with markers, crayons, paint, or other art supplies. *This activity is not classroom tested.* To apply building techniques and knowledge about gears to an activity challenge. RCX or NXT LEGO kits Example photos of toys that create spin art Assortment of extra LEGO pieces, especially gears and beams Engineer’s Planning Sheet Markers, crayons, paint, or other art supplies Tape (to tape markers, crayons etc. to LEGO pieces) Large sheets of paper to draw on Collect necessary materials Tape down large sheets of paper to floor if necessary Photocopy worksheets Arrange students into groups of 3 Decide how you will distribute extra pieces and drawing utensils Write design requirements on the board Review gears and gear ratios Vocabulary: Prototype Engineering Design Process Gears Gear ratio Tell students that in this challenge they will be making spin art. Explain to them what spin art is and the different ways they can go about making it. Spin art is created by any medium spinning in some manner, whether it is the marker drawing in circles, paint being spun, or paper being rotated, etc. Students may attach these things to a car that they program, or a stationary object, or whatever they choose; this activity is very open ended for students design-wise. Show students different pictures and/or videos of spin art toys, explaining what they do and how they work. Also, it may be a good idea to review how gears work. Explain the engineering design process, emphasizing the prototype and the redesign. Tell them the requirements for their spin art makers. Examples of requirements are:       Must have at least three gears       Can be manual or electric       Must use two different mediums (i.e. markers and paint, paint and crayons, etc) Allow the class to brainstorm different ideas for their spin art design. Have them plan out and draw their design on the engineering planning sheet. Distribute materials and have students start building. You may have to assist students with taping markers to their project. After the students finish, review the activity with the class. Have them share their ideas, ask groups to explain what the hardest part of the challenge was, etc. Have students add more gears Have students add more drawing utensils (more markers, etc) Have students put their drawing utensils on different axes (i.e. one paintbrush horizontal and one marker vertical) Have students add a sensor that causes something on their spin art maker to perform some act (i.e. when the light sensor senses white, the blue marker starts spinning) http://sites.tufts.edu/stompactivitydatabase/files/formidable/a.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/b.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/c1.pdf

## Hand Mixer

Name of Activity Hand Mixer Kara Miranda hand mixer, gears, gear ratios, not classroom tested, prototype, Engineering Design Process, 4-6, 7-9, 2 Hours Total NXTs 4, 5, 6, 7, 8, 9+ 2 Hours Total Students will design and build a hand mixer, learning how to use different gears in a variety of ways. *NOTE: not classroom tested. To apply building techniques and knowledge about gears to an activity challenge. RCX or NXT LEGO kits Photos of different hand mixer designs Assortment of extra LEGO pieces, especially gears and beams Building Design Sheet Collect necessary materials Photocopy worksheets Arrange students into groups of 3 Decide how you will distribute extra pieces Write design requirements on the board Review Gears and Gear Ratios Vocabulary: Prototype Engineering Design Process Gears Gear Ratios Tell students that in this challenge they will be building a hand mixer. Show students different pictures and/or videos of hand mixers, explaining what they do and how they work. Also, it may be a good idea to review how gears work. Explain the engineering design process, emphasizing prototype and redesign. Tell them the requirements for their hand mixers. For example:      Must have at least three gears      Can be a manual or electric hand mixer Allow the class to brainstorm different ideas for their mixer design. Have them plan out and draw their design on the Building Design Sheet. Distribute materials and have students start building. After the students finish, review the activity with the class. Have them share their ideas, ask groups to explain what the hardest part of the challenge was, etc. Have students add more gears. Have students make the bottom of their hand mixer spin faster or slower by adjusting the gear ratio. http://sites.tufts.edu/stompactivitydatabase/files/formidable/109_image_1.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/109_image_2.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/Building-Design-Sheet.pdf

## Mountain Rescue

Name of Activity Mountain Rescue STOMP car, climb, incline, gears, gear ratios, NXT NXTs 4, 5, 6, 7, 8, 9+ 1 Hour Total Students will build or modify a car to climb a steep incline using gears. - To learn about gears and gear ratios. - To learn about forces involved with inclines and gears. - One NXT car per group. - An assortment of different sized gears. - Steep incline. Construct a steep incline that is wide enough for an NXT car to climb. Arrange students into groups of two. Photocopy enough worksheets for the class. Distribute necessary materials. Gears can be used to increase or decrease power in a machine; for example, a can opener. Gears are used in many modern inventions and everyday devices. Gears can also be used to change rotational motion. Gears ratios are used to compare gears of different sizes. The size of a gear is measure by the number of teeth or cogs that are on the outside of the gear. The formula for a gear ratio is: (number of teeth on gear #1)/(number of teeth on gear #2). Gear ratios can be used to detrmine how many turns of the second gear their will be for the number of turns of the first gear. The gear that is mechanically turned by a person or a motor is called the drive gear. The gears that turn as a result of the drive gear being turned are called the followers. gears turn in opposite direction of the gears directly next to them. A car driving up an incline has more forces acting against it than a car driving on a flat surface. Gravity has a different affect on a car driving up a ramp and pulls the car down the slope. As a result, a car driving up a ramp requires more power. Friction is also an important factor for a car driving up a ramp. The more friction the better grip a car will have on the surface of the ramp and the less likely the car will be to slide back down the ramp. Vocabulary: gears gear ratios drive gear follower gear gravity friction slope Discuss gears and gear ratios with students. Have students fill out worksheets on gears and gear ratios. Discuss the forces acting on a car driving up a ramp. Discuss the difference between a car that drives on flat ground and a car that drives up a ramp. Have student build an NXT car or provide a pre-built NXT car. These first cars should not have gears attached. Have student program their cars to drive for about 20 seconds (enough time to climb the ramp) at a power of about 75 (a power too great for the car to climb the ramp without falling off). Allow students to try to drive their car up the ramp. Come together as a class and discuss why the cars had difficulty climbing the ramps. Tell students that they are not allowed to reprogram their cars, but must use gears to give their cars enough power to climb the ramp. Have students add gears to their cars and test the design on the slope, let them try different gear ratios and combinations. Students can attach a proximity sensor to their car to prevent the car from falling off the edge of the ramp. http://sites.tufts.edu/stompactivitydatabase/files/formidable/63_image_2.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/63_image_3.jpg http://sites.tufts.edu/stompactivitydatabase/files/formidable/Gear_Ratio_Worksheet.pdf http://sites.tufts.edu/stompactivitydatabase/files/formidable/Gears_Worksheet.pdf http://sites.tufts.edu/stompactivitydatabase/files/formidable/mountain_rescue.doc

## Bicycle Unit: Bike Gears

Name of Activity Bicycle Unit: Bike Gears STOMP bicycle, gear ratios, gears, gearing up, gearing down, teeth, cogs, drive gear, follower Non-LEGO 4, 5, 6 1 Hour Total Students will be introduced to gears using a real bike as an example. Students will use this knowledge to do an activity about gear ratios. - To relate the concepts of gears, gear ratios, and gearing up and down to actual bikes. - At least one road bike. - As many trainers as bikes. - Measuring tape. - Activity worksheets. - Set up the bike(s) on the trainer(s). - Place a mark on the rear wheel using tape or chalk. - Make enough worksheet copies for each student. - Arrange students in groups if there is more than one bike to look at. Gears are wheels with teeth, or cogs. These teeth come in contact with each other and interlock so that when one gear turns the other gear also turns. Interlocking gears of different sizes turn at different rates. The gear that is manually turned is called the drive gear. The other gear is connected to a wheel or axle that needs to be turn; this is called the driven gear or follower. On a bike, gears are connected by a chain. The driver is the gear connected directly to the pedal. The back wheel of the bike is connected to the pedal by a chain. Usually there is a mechanism on the handle bars that changes the gear ratio; in other words, moves the chain to gears of different sizes on the driver and driven gears. Gear ratios are a set of two numbers that tell how fast one gear will spin in relation to the other gear. A gear ratio is a direct function of the number of cogs on each gear. To calculate a gear ratio, count the number of teeth on the drive gear and divide it by the number of teeth on the driven gear. Bicyclists gear up and down depending on the conditions of where they are riding. Gearing up is when a bicyclist chooses a high gear ratio; there are more teeth on the drive gear than then driven gear. This means that you go very far on one pedal, but can be good when you want to climb hills. This is because with one pedal, the wheel on the back gear spins several times. Gearing down is when a bicyclist chooses a low gear ratio and there is a lower gear ratio closer to 1:1. This means that for each pedal the rear wheel turns a lot; a bicyclist can not go far, but each pedal provides more power. Gearing down is good for going uphill, or just starting out. Vocabulary: Gears Cogs Teeth Gear Ratio Drive Gear Driven Gear Gear up Gear down Choose the large gear in the front, and the small gear in the back. Have the students count the number of cogs on both gears. Slowly turn the pedal one time and see how many revolutions the rear wheel makes (using the marker on the rear wheel to see the revolutions). Calculate the gear ratio by dividing the number of cogs on the front gear by the number of cogs on the rear gear. Based on the fact that circumference = 2*pi*radius determine how far the bike would have gone in one revolution of the pedal Measure the radius of the wheel. Multiply the radius by 2*pi (6.28). Multiply this number by the number of revolutions that the wheel made for one pedal. Have students fill out the attached worksheet for different gear ratios. Demonstrate cadence and ease of pedaling for each setting. When the students have completed the worksheet, bring the class together for discussion. Ask students: What happened to teh gear ratio as the rear gear got larger adn larger? Did that make it easier or harder for the cyclist to pedal? Which of the tested gear ratios would you want to use to climb a big hill? Which of the tested gear ratios would you want to use to go down a hill really fast? - Have students calculate how far a person’s feet travel in one rotation (circumference of the circle that you foot would make in the air using the length of the pedal as the radius). - Have students use the gear ratios to calculate how far a bike can go with one pedal in a high gear ratio (e.g. 1 to 4, or a low gear ratio 1 to 1). http://sites.tufts.edu/stompactivitydatabase/files/formidable/gear1.pdf http://sites.tufts.edu/stompactivitydatabase/files/formidable/gear2.doc http://sites.tufts.edu/stompactivitydatabase/files/formidable/gear3.pdf

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