Fanning the Flames Activity Guide Activity Provided Courtesy of Techbridge (http://www.techbridgegirls.org) In this activity, youth explore some of the challenges related to cooking meals in regions where electric or gas stoves are scarce. They learn about potential problems (such as respiratory diseases) with using open fires for cooking, and then design and build their own stoves. Activity Type Intermediate/Advanced Grade Level Grades 5-12 Grouping Activity Time Preparation Time Pairs 2 hours 1 hour to gather materials (see Advanced Preparation) Career Connections Engineer Framing Question How can I build a stove that is better designed for cooking than an open fire? Learning Objectives As a result of this activity, youth will be able to: Identify challenges with using open fires for cooking Identify some of the key qualities needed in cook stoves designed for use in developing nations Develop, test and refine a design Key Terms Engineering design process Three-stone fire Materials Per group: A picture or video of a three-stone fire (see Resources for links) Long-handled lighter or a box of long-handled matches
A variety of fuel types, such as dried sticks, wood, charcoal, pieces of kindling, paper or dried grass, in quantities large enough for youth to use as fuel for their stoves Optional: Digital scale that weighs grams Optional: One or more sample stoves (see Advance Preparation) Hair ties Ash bucket Bucket of water Per pair: One or more clean, empty soup cans (see Advance Preparation) At least three clean, empty small cans, such as those used for tuna or cat food (see Advance Preparation) A small (e.g., two-cup), lightweight pot with a heat-safe handle OR an additional small empty can Roll of heavy-duty aluminum foil Four- to six-foot length of 1.5mm aluminum wire (such as bonsai wire) Optional: Additional lightweight metal materials for building stoves, such as: o Heavy-duty aluminum muffin tin pans (not muffin tin liners) o Hardware cloth and tin snips for cutting it Can opener (preferably one that leaves smooth rather than sharp edges) Optional: Churchkey can opener Container of water Stopwatch Digital thermometer Potholder Pot-lifter tongs Long-handled tongs Per individual: Copy of the Stove Design Challenge handout Goggles Pair of rubberized gloves (such as gardening gloves) Advance Preparation Select an open, outdoor, fire-safe location to use for testing stoves during this activity, such as a school parking lot. Gather clean, used tin cans that youth can use to build stoves. You will need two sizes: medium (10-12 ounce) cans, such as that soup come in, and smaller (3-6 ounce) cans, such as those tuna fish comes in. Be sure the cans you collect have bottoms with edges that can be opened with a can opener; some soup can bottoms have rounded edges that can t be opened. Optional: Prior to beginning the activity, build one or more sample stoves that youth can use as inspiration. See Resources for links to information on building a Rocket Stove, an efficient stove that uses insulation as part of the design. Note that the Rocket Stove requires cutting tin cans with tin snips, a procedure that youth won t use during this activity as it can create dangerously sharp metal edges. 2
Introduction (10 minutes) 1. Show and describe a three-stone fire. Ask youth: What do you use for cooking at home? What is the source of fuel? Explain that in many parts of the world, people don t have access to electricity or natural gas in their homes, so they have to cook food in other ways. Show the group the picture or video of a three-stone fire. Tell the group the following: Three-stone fires are a type of open fire commonly used for cooking in some developing nations. These fires burn biomass material from plants or animals such as wood, leftover plant material from farming, or animal dung. Such fires are often used indoors (they are also used outdoors). The fuel for the fire is often gathered by women and girls, who may have to travel up to several miles to find the wood, and may carry very heavy bundles of wood back to their homes. 2. Discuss challenges of using three-stone fires for cooking. Give youth a minute or two to observe the fire, and ask the following questions: What do you think might be some challenges or problems with using a fire like this for cooking? Possible answers: If such fires are used for cooking indoors, the people using them will inhale smoke, which is bad for health, and sparks from the fire could be dangerous. It may be hard to cook on the fire because the level of the flame can t easily be controlled. Spending such a long time looking for fuel is hard work and may keep women and children from doing other tasks or going to school. The fires don t make the most efficient use of fuel, as heat escapes into the air and heats up the stones. (Youth may not be familiar with the term efficiency; see Extensions for more information about efficiency.) TIP: Make sure that youth understand that one of the main problems with cooking on open fires is that particles in the smoke are inhaled into the lungs. The United Nations estimates that 1.9 million people, mostly women and children, die each year from health issues related to cooking on or heating with open fires lung diseases, heart disease and low birth weight. You can also tell the group that gathering fuel for fires can be dangerous for women and girls; in some areas (especially conflict zones), they may be attacked by men if they have to travel far from home for such tasks. What might be some advantages of using a fire like this for cooking? Possible answers: Three-stone fires use basic materials that are readily available in many parts of the world, are free to make, and don t require special skills to operate. 3
Hands-on Activity (1 hour 35 minutes) 1. Describe the activity and discuss fires. Tell youth they will take on the role of engineers as they work in pairs to design a stove out of tin cans and foil that can be used to heat up water in a small pot. They will test the stove by lighting a fire, placing a pot on the stove, and measuring the temperature of the water after the fire burns. Show the group the pot or small can they will use to heat water. Have youth meet in pairs to discuss the following questions: Where have you seen a fire before in your own life? Based on your experience, what does a fire need to burn? Possible answers: Fires need fuel, oxygen (younger youth may just say air ) and an ignition source (something hot enough to heat the fuel to the point where it starts to burn). Have pairs share their answers with the group and make a list of fire needs. Then ask: What are the different components of a stove that you will need to include in your design? Possible answers: Stoves need a place to put fuel, a way to contain the flames and a place to put the pot. How can you design a stove that includes everything a fire needs to burn? Possible answers: Youth will need to design stoves that let oxygen reach the fuel, allow a user to add more fuel to the fire once it s started and allow that user to place an ignition source (such as a flame from a match or lighter) into the fuel. TIP: Particularly with younger youth, you may want to stress that oxygen needs to be able to flow over the fuel; a fire is not likely to burn well if air is coming in only at an opening above the fuel as the air will not draw (be sucked into the flames). Therefore, a stove designed so that the fuel sits at the bottom of a can with the only opening at the top of the can may not be successful. However, you may also choose to let youth discover this principle on their own. Tell the group they should keep this information in mind as they build fires in their stoves. 2. Go over safety information. Give each kid a copy of the Stove Design Challenge handout, and do the following: Have a volunteer read the safety rules on the handout. Go over any questions youth may have. Make it clear only instructors will be allowed to start fires, and that youth should wear their gloves at all times when working with the metal cans. 4
If you are giving youth the optional churchkey, show them how to use it to poke holes in the cans, and tell them they need to be careful because the punched-out pieces of metal have very sharp edges. Show the group the location of the water and ash buckets. 3. Design and build stoves. Divide the group into pairs, and do the following: Give pairs safety goggles, gloves and the materials they can use for the stoves. Have partners work together to design and build a stove that they think will heat water (Step 1 on the handout). TIP: See Extensions for a more advanced design and testing approach that you can use with older youth. SAFETY TIP: Make sure everyone in the group is following safety procedures as they work, and wearing goggles and gloves. Depending on the age group that you are working with, you may also want to discuss the differences between a material burning and melting, and make sure that youth understand that they can only use non-flammable, non-meltable materials in their stove designs. 4. Discuss fuel and fire building. Once the stoves are built, show the group the different kinds of fuel available. Ask youth the following questions: Have you ever lit a fire in a fireplace or for a campfire? What did you need to do to get it started and keep it going? Possible answers: Fires usually need small, quick-burning materials (such as paper or small pieces of wood [kindling]) to get started, and bigger, slower-burning materials such as larger pieces of wood to keep going. How do you think the fuel should be arranged in a fire? Possible answers: Fuel should be arranged so the pieces that catch fire quickly (paper and kindling) are underneath, and larger pieces (sticks or logs) are on top, so the flames from the paper/kindling will light the bigger pieces. There also needs to be enough space in the fire for air to circulate; tightly wadded pieces of paper or closely packed sticks may not light or stay lit. 5. Test stoves. Have pairs select the fuel that they will use in their fire. Give them digital thermometers. TIP: Optionally, you can limit pairs to a set weight for the fuel (such as 10 grams), and have them weigh out their fuel on a digital scale. Limiting fuel will make the testing process more consistent and ensure that fires don t burn for too long, but the process of weighing the fuel requires additional time. Have pairs build their fires and put the pot on top of the stove; circulate among the pairs to light fires. Make sure that the stoves are a safe distance (a few feet) apart. Have pairs do the following (Step 2 on the handout): Observe the fire from a safe distance Use the stopwatch to keep time 5
At the five-minute mark, remove the pot from the fire with the pot-lifting tongs and measure the temperature of the water with the digital thermometer When they are done measuring, dump water from the bucket onto the fire, wait for the stove to cool down, and put the ashes and fuel in the ash bucket, using tongs to hold the stove/fire container. TIP: You can take different approaches to the stove observation process depending on the age and maturity of the youth in your group. You may want to keep young youth at least a few feet away from lit stoves. However, you may want to let older youth work on their fires by blowing on them (from a safe distance) or moving fuel around with long-handled tongs. If you take this approach, be sure to lay some ground rules (e.g., only one partner works on the fire at a time, don t hold a hand over the flame, don t put the thermometer in the fire, etc.) You can demonstrate with one pair s stove what is OK to do and what isn t. Ask youth to also walk around and observe the stoves that other pairs have built. TIP: If it is windy out, pairs may have trouble getting their fires to stay lit. You can encourage them to build wind shields or find another way as part of the stove design to protect fires from the wind. 6. Discuss stove observations. Bring the group together and ask the following questions: Did your fire stay lit? Did the water heat up? Why or why not? What did you learn by observing other pairs stoves? What do you want to change about your stove design, and why? 7. Redesign, rebuild and retest stoves. Have pairs use their observations to redesign, rebuild and retest their stoves (Steps 3 and 4 on the handout). Reflection and Discussion (15 minutes) 1. Have pairs share designs. Give several pairs the opportunity to share their stove designs with the group, describing the design and redesign process and the results of their tests. 2. Discuss the design process. Ask the group: Why did you make the design choices you made? What factors did you consider? Possible answers: Pairs may have considered the fuel that they had available, what they knew about how fires work, the materials that they had on hand, or other factors. Do you think your stove design is an improvement over the three-stone fire? Why or why not? What did you learn about building and using fires during this activity? 3. Reflect on cookstove use around the world. Ask the group: Think about people using stoves for cooking around the world. How might a stove user s needs be different in one place than in another? Possible answers: Different fuels may be available (such as wood or animal dung), and that may mean that one stove design works better than another. A variety of foods might be cooked, and even the same 6
foods might be cooked in different ways (e.g., stir-frying vs. boiling) all of these differences may mean stove designs need to be different for different regions. TIP: Stress to students that cookstoves, and indeed many technologies, need to be designed with consideration for the place they are used and the people using them. Many successful engineering projects are designed by people living in the communities where the products or services will be used, or designed in consultation and collaboration with the users. What are other methods besides burning biomass that can be used for cooking? (Think about how your family cooks). What are some advantages and disadvantages of those methods? Possible answers: Other cooking methods include burning natural gas or using electricity (e.g., to power an electric stove or a microwave). Advantages include that such methods may be safer, have few or no negative health effects on users, may be more efficient than burning biomass (because more of the energy is used for cooking rather than lost as heat in the environment), are easier to control, and don t require users to collect fuel. Disadvantages include that natural gas or electricity may not be available in a region, may be too expensive or difficult to bring to a home, may be too costly to use, and may require appliances that the very poor don t have access to. TIP: If time permits, you can discuss or show videos about alternative ways to get electricity and cooking gas to people in poor and rural areas, such as the use of solar cells and biodigesters that produce methane gas that can be used for cooking. Journal Ideas Have youth answer the following questions in their journals: How does your family cook food at home? If you didn t have a stove or a microwave, how could you cook your food? What would you use for fuel? Extension If you are working with older youth, you may want to give them more options for the stove design challenge (besides the challenge of heating water). One approach is to let youth choose one problem with the threestone fire (such as smoke emissions), and build a stove they think improves on this problem as compared to the three-stone fire. Youth can design their own protocol for testing out whether they have succeeded (such as building a three-stone fire themselves and comparing it with their stoves). If you are working with older students, you can also discuss the concept of fuel efficiency with the group. You could ask youth to define efficiency (the ratio of work done by a machine or device in relation to the amount of energy supplied to it) and describe what it would mean for a stove to be fuel-efficient (for example, a fuelefficient stove might use less fuel to heat up water or food as compared to another stove or three-stone fire). Youth could then have the option of choosing fuel efficiency as the factor they want to improve on with their stove design. 7
Resources Information about three-stone fires http://www.youtube.com/watch?v=bjn8osrfqaq http://www.youtube.com/watch?v=akyfqddphle http://greencooking.wikidot.com/three-stone-cooking-fire http://www.appropedia.org/three_stone_cooking_fire http://www.grassrootsengineering.org/testing-the-efficiency-of-firewood-stoves.html 8
Stove Design Challenge (Handout) What does your family use for cooking a gas or electric stove? Maybe you cook some meals in a microwave or on a hot plate? Around the world, many people don t have access to appliances like these for cooking, or the electricity or gas needed to use them. Instead, they cook over fires, using biomass, which is material from plants or animals, like wood, leftover plant material from farming, or animal dung. Your Challenge In this activity, you are going to work with a partner to design a stove out of tin cans and foil. Your challenge is to see how hot you can make water in a pot placed on the stove. Safety Rules You will be working with fire and sharp metal during this activity. Be careful, listen to your instructor, and follow all of the safety rules! They may cook over an open fire such as a threestone fire, a fire surrounded by three rocks with a cooking pot placed on top. They may also cook on a stove that surrounds the fire with metal or clay. Tie back long hair Tuck in loose clothes Always wear safety goggles and gloves: cut metal edges are very sharp Do not light the fire ask your instructor to light it! Stay far back from lit fires and watch for sparks Know where the water bucket is at all times, and use the water to put out anything that catches fire beside the fuel in your stove Put water on your fire when you are done and wait for the stove to cool down Put your ashes in the ash bucket 9
Step 1: Design and Build Your Stove Look at the materials you ve been given to build your stove, and brainstorm design ideas for a stove that you think will heat up the water in the pot you ve been given. HINT: As you work on your design, try playing with the materials and seeing how you might fit them together. Sketch your stove design below: Once you are happy with your stove, build it, using the materials you ve been given. Step 2: Test Your Stove Build a fire in the stove, put the pot of water on top, and have your instructor light the fire. Use a stopwatch to time your fire, and when it has been burning for five minutes, carefully use the pot-lifting tongs to take the pot off the fire and measure the water temperature with the thermometer. As you are watching your stove, look for the following: Does the fire stay lit? Does all of the fuel burn? Does the water in the pot heat up? Are there any problems that you notice? Once your fire has burned out, put water on the fuel, wait for the stove to cool down, and use tongs to put the ashes in the ash bucket. 10
Step 3: Redesign Your Stove Based on your observations, redesign your stove so that it will get the water hotter. Draw your redesigned stove: Step 4: Rebuild and Retest Your Stove Rebuild your stove based on your new design. Then, test the stove by building a fire, putting the pot on the stove, timing the fire, and measuring the water temperature after five minutes. Does the water get hotter? 11