4-PS3-2 Make observations to provide evidence that energy can be transferred from one place to another via sound, light, heat, and current.
4-PS3-4 Use scientific concepts to design, test and improve the equipment that can transform energy from one form to another.
Science - Grade 3-5
We all love barbecues, but smoke produced by grilling often contains pollutants that damage health. Can we utilize pollution-free solar energy to cook food? In this lesson, we are going to make a solar oven to cook chocolate sandwich biscuit based on the principle of light reflection.
According to the NGSS standard engineering design requirement in 3-5 grades, the course is divided into 3 parts, they are respectively “DEFINE ENGINEERING PROBLEMS, DEVELOPING POSSIBLE SOLUTIONS, OPTIMIZING THE DESIGN SOLUTION”. Just like engineers, students will find problems, set goals, design plans, build and test models, optimize and improve models, and finally complete the engineering design task.
Activity 1 DEFINE ENGINEERING PROBLEMS
Have you ever cooked outdoors? When grilling or camping outdoors, charcoal is often burned to heat food. This will pollute the environment to a certain extent. Is there an environmentally friendly method?
In the previous project, we have learned the concept of energy. Many kinds of energy can be converted into heat energy. For example, when burning charcoal, the chemical energy of charcoal is converted into heat energy. Think about it, what other energy can be converted into heat? Can it be convenient for us to cook food outdoors without polluting the environment?
Solar energy is a good choice. The sun's radiation can heat objects. Let's make a solar oven together!
Make a solar oven to cook food with the Sun.
Activity 2 DEVELOPING POSSIBLE SOLUTIONS
After determining the engineering goals, let us follow the process of “Brainstorming-Drawing Prototype Diagram-What You Need-What You Do-Test and Evaluate”to develop a solution and complete the building of a solar oven.
Let’s first brainstorm how to build a solar oven. In the process, try drawing a prototype of the solar oven.
In the brainstorming, we have initially understood the function and structure of the solar oven. Try drawing a prototype diagram. In the production process, the prototype diagram will be an important reference.
With the above steps, a simple solar oven is completed! On a shining day in the summer, at about 12 o'clock and 3 o'clock, put the solar oven outside, then we can enjoy delicious chocolate sandwich biscuits after a while!
Do you think solar ovens can be optimized? Can the oven collect more sunlight to heat the food? Try to propose an optimization plan to improve the efficiency of the solar oven.
Activity 3 OPTIMIZING THE DESIGN SOLUTION
Let us continue the process of “Brainstorming-Drawing Prototype Diagram -What You Need-What You Do-Test and Evaluate” to carry out optimization and iteration of solar ovens.
Through brainstorming, we optimize the design of the solar oven, try optimizing the prototype figure, and mark the materials and functions of each part.
Prepare the following BOSON modules and other materials.
The table of temperature change of the solar oven:
On a shining day in the summer, at about 12 o'clock and 3 o'clock, put the solar oven under the sun. We can enjoy delicious chocolate sandwich biscuits after a while! If the weather is not so good, we can also use a warm-light lamp as the light source to continue the experiment.
Note 1: If it is in a hot summer, the temperature of the solar oven may be very high. Remind students to use anti-scalding gloves to prevent burns.
Note 2: Chocolate will not melt until it is above 30 degrees. If it is in the cold winter, the room temperature is low and the temperature of the solar oven does not reach 30 degrees, the chocolate will not melt. In winter, we can change this lesson into "solar plant greenhouse". The goal is to use solar energy to create a warmer living environment for plants in the cold winter. Please pay attention to the ventilation of the experimental device this time.
When the lights from the sun reaches the earth, they are reflected by the aluminum foil and pass through the plastic wrap, heating the air inside the pizza box, so the temperature in the pizza box will rise, just like a car gets hot in summer. The newspaper in the pizza box plays a role in insulating.
Compared to traditional ovens, solar ovens are a low-cost and eco-friendly technology. Although it takes a longer time to cook, it does work.
In this activity, we made a very simple solar oven, and we can also try adjusting many variables in the solar oven design to make it better. Such as changing the angle of the reflector baffle, or using color with better heat-absorbing ability in the oven to improve the efficiency of the solar oven.
Different colors have different heat absorption abilities. If a piece of black paper is put at the bottom of the oven, can the efficiency of the solar oven be improved? Let’s continue to explore it!
When light hits on an object, three things happen: part of the light can be absorbed by the object, part of the light can be reflected by the object, and part of the light can continue to spread through the object.
Different colors reflect and absorb light differently. Dark colors, especially black, will absorb light more, and the absorbed light will be converted into heat. Light colors reflect light more easily and absorb less light. This is why wearing a black shirt in summer feels hotter than wearing a white one!
In this project, we made a solar oven using the pizza box, plastic wrap, and newspaper. With the knowledge of light reflection, we optimize the design of the oven. In further exploration, we have mentioned that the efficiency of the oven can be improved with the change of the angle of the reflector baffle and the choose of a better color in heat absorption.
The project is going to an end, please remove cables, and put all the BOSON modules back into the kit.