5-PS1-3 Make observations and measurements to identify materials based on their properties.
4-PS3-2 Make observations to provide evidence that energy can be transferred from one place to another via sound, light, heat, and current.
Science - Grade 3-5
There are many types of materials used in construction and their thermal insulation capacities are various. What materials are best for building a comfortable house? In this lesson,we will mainly explore the thermal insulation performance of wood, plastic, and metal so as to introduce the concept of heat, leading students to find out which kind of material has better thermal insulating performance as well as get to know the basics about heat transfer.
Whether it's in the hot equatorial region or the cold Arctic, people all want a very comfortable indoor temperature. Imagine that we have just arrived at a deserted tropical island, where the scenery is beautiful, but it's pretty hot... There are three kinds of materials on the island that can be used to build a house: wood, plastic and metal sheet. If we want to live in a cool and comfortable house, which one should we choose? Take a guess!
The thermal insulation performance is closely related to the transfer speed of heat. The better the thermal insulation effect, the slower the heat transfer speed. Will the three materials wood, plastic and metal transfer heat at the same speed?
This lesson mainly contains two parts: 1. Feel the temperature of the three materials by touching. 2. Use the BOSON temperature sensor to explore the thermal insulation capacity of the three materials so as to find out the most suitable one for building a house.
Part 1 Observation: Which material feels colder?
It is known that in winter, metal feels colder than plastic and wood, while in summer, it feels hotter than the latter two materials. Why is that?
If we put a piece of ice in a wooden cup, a plastic cup and a metal cup, which will feel colder after keeping still for a while?
The experiment shows that the metal cup feels colder than the other two cups, which indicates that metal has the fastest heat transfer speed among them. Wooden cups and plastic cups feel almost the same, so they transfer heat at about the same rate.
When building a house, which kind of material should we choose to achieve better thermal insulation performance? Take a guess！
Part 2 Measurement: The thermal Insulation Performance of different material
In this experiment, we need a wooden cup, a plastic cup and a metal cup with similar volume and thickness, put ice blocks of the same size into each cup, and then use the BOSON temperature sensor to measure the temperature change of the three cups. Present the thermal insulation capacity of the three materials by the experimental data and record values in the table below.
If the experiment is carrying out in summer with high temperature, then shorten the experiment time in case the ices melt completely.
Prepare the following BOSON modules and other materials.
1. Build an experimental circuit to detect the environmental temperature.
2. When the circuit is built, complete the following steps.
Tip: In the actual experiment, for saving time, teachers can arrange three groups of students to choose different materials and do the experiment at the same time, and then summarize the data in one table.
The reference experiment data are shown below(at indoor temperature 20℃):
The experimental data shows that, for the heat transfer performance: metal>wood>plastic, which also means, for material thermal insulation capacity: metal
Now, do you know what material we should choose to build a house?
From the experiment, we get known to the thermal insulation of material, also heat transfer performance. Next, we will get into more details about how heat is transferred.
Take wood and metal as examples. In a cold winter, the temperatures of wood and metal outdoors are almost the same as the ambient temperature.
When we touch metal, since our hand is warmer than the metal, the heat will be transferred from the hand to the metal. Metal material transfers heat so quickly that when the heat is just transferred to the part where our hand touches the metal, it will be transferred out by other parts of the metal, which will make us feel cold when touching it.
When touching a wood, similarly, that heat will be transferred from the hand to the wood because its temperature is higher than the latter. The difference is that, since the wood transfers heat slowly, the heat absorbed by the wood will accumulate at the part where our hand touches the wood, as a result, it does not feel so cold compared with the metal.
Metals are called good conductors of heat since they can speedily transfer heat, whereas materials that transfer heat slowly like wood, plastic, paper, air, and cloth are poor conductors of heat.
Metals among solids are good conductors of heat, such as silver, copper and aluminum. Other solids are mostly poor conductors of heat, such as stone, ceramics, glass, wood, etc. And materials like, wool, feathers, fur, cotton, asbestos have very poor heat transfer performance, which can save the heat emitted by the human body and keep the body warm. So people often wear cotton-padded clothes, sweaters or down jackets in winter.
In this project, we explored the scientific principle behind the common phenomenon“Why do metals feel colder than plastic”, finished the research experiment using the BOSON temperature sensor, and learned the basics about good conductors and poor conductors of heat. So the question at the beginning of this lesson can be answered now.
That’s all for this lesson. Please put all BOSON modules into the original box.
Many mugs are made of stainless steel, why do they still have such a good thermal insulation effect?