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Project Based Lessons - Chemical Reactions & Engineering Design
Step 1Help students identify the problem that their engineering design process will try to solve.
The following story is included on the Student Activity Sheet. This story introduces the design challenge and serves as motivation for the lesson. Either read it aloud or have students read it silently.
Imagine that you are a volunteer with a reptile conservation center. One important project is to rescue reptiles (turtles, snakes, and lizards) that are in the unlucky position of living in the path of new construction. Typically, in these cases, animals move. They search for new homes and food sources nearby. However, eggs cannot crawl, slither, or swim to another location. And construction projects will not wait for eggs to hatch.
You have talked with construction workers at a site who agreed to notify you if they find reptile eggs. The center is able to incubate the eggs until the babies hatch and then return them to the wild. Your role is to design a reptile egg incubation device that keeps an egg warm and safe as it is transported from the worksite to the reptile conservation center.
Reptile eggs are leathery and soft. While they are not prone to crack easily, they need to remain in the same orientation they were originally laid— whatever is facing up, must stay facing up. They cannot be flipped, turned, or jostled. Very importantly, the eggs must be kept warm, but not too warm, to properly develop and hatch.
You have a job to do before the first batch of eggs is found— build a temporary portable reptile egg incubator device that will keep one egg warm and properly positioned while you take it to the reptile conservation center. Let's give these young lizards, turtles, and snakes their best chance at life!
Tell students that in this lesson, they will conduct activities to develop a portable reptile egg incubator device. The device will need to warm, support, and protect one egg.
Step 2Show the video of different heat packs to serve as a starting point for the design of a portable reptile egg incubator.
Three Types of Heat Pack
Lesson 6.11 Video
Tell students that there are a variety of heat packs that use different chemical processes to heat up. One of these processes could be used to begin development of their egg incubator device.
One type of heat pack contains a fine iron powder, salt, and water in a pouch that is permeable to air. When it is exposed to air, the iron begins to rust. This rusting process produces heat.
Another type of hand warmer contains a solution of the chemical sodium acetate and a small metal disc. When the disc is bent, crystals of sodium acetate begin to form. This process of changing from a liquid to a solid produces heat.
Another type of heat pack contains a solid, such as magnesium sulfate, and a pouch of water. When the pouch of water is broken, the magnesium sulfate begins to dissolve. Dissolving this type of magnesium sulfate produces heat.
Let students know that they will begin the development of their egg incubator device by using a dissolving process.
Step 3Discuss the criteria and constraints for a successful design.
Explain to students that the features the device must have are called the criteria.
Ask students:
If you think about a heat pack as the basis for an egg incubator, what basic features does your device need to have?
Explain to students that possible problems that might prevent the design from successfully meeting all the criteria are called constraints.
Ask students:
What are some factors that might prevent the design from successfully meeting all these criteria?
The activity sheet will serve as the Evaluate component of this lesson. The activity sheets are formative assessments of student progress and understanding.
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The activity sheet will serve as the "Evaluate" component of each 5-E lesson plan. The activity sheets are formative assessments of student progress and understanding. A more formal summative assessment is included at the end of each chapter.
Students will record their observations and answer questions about the activity on the activity sheet. The Explain It with Atoms & Molecules and Take It Further sections of the activity sheet will either be completed as a class, in groups, or individually depending on your instructions. Look at the teacher version of the activity sheet to find the questions and answers.
Step 4Continue the story about rescuing reptile eggs and determine the incubation temperature requirement.
The student activity sheet returns to the story about transporting reptile eggs from a construction site to a reptile conservation center. Have students look at the text message as well as the reptile egg identification page on their activity sheet to identify whether these eggs belong to a snake, turtle, or lizard. Each type of reptile egg has a different incubation temperature requirement.
Ask students
Step 5Have students begin developing their device by dissolving different amounts of calcium chloride in water.
Ask students
Question to Investigate
Does the amount of calcium chloride dissolved in water affect the temperature change?
You will need:
Note: The bulb of each thermometer must be completely submerged in order to accurately measure the temperature of the liquid. If using thermometers with a thin plastic backing, use scissors to clip the bottom off so that the bottom of the bulb aligns with the bottom of the backing. This allows you to use less liquid which allows for more dramatic changes in temperature.
Note: Complete steps 5 and 6 as soon as possible after step 4.
Procedure
Dissolve calcium chloride
With the thermometers still in the cups, gently swirl both cups and check the temperature of both. Record the highest final temperature each reaches in the chart on the student activity sheet.
Expected Results
The solution with more calcium chloride increases to a higher temperature.
Note: Complete steps 5 and 6, found on the next page, as soon as possible after step 4. If students have worked with calcium chloride and baking soda before, ask the following questions before continuing the procedure.
Ask students
Add baking soda
Expected results
The solution bubbles and the temperature decreases.
Ask students
Since adding baking soda makes the temperature go down, does this mean that it should not be used in the design of the device? Not necessarily. Maybe it can be used so that gas is produced but with enough calcium chloride to make the temperature high enough. There would need to be some kind of balance between the amount of calcium chloride and baking soda so that the right temperature is reached, and enough gas is produced to hold the egg in position and protect the egg.
Give students time to complete this page of their student activity sheet.
This may be a good stopping point for the first portion of this lesson.
Step 6Have students test a combination of calcium chloride, baking soda, and water.
Tell students that they will combine calcium chloride, baking soda and water to try to get within the right range for snake eggs. First, they will mix the calcium chloride and baking soda together and then add this mixture to water.
Ask students
If the temperature is too high, what can you do? What if it is too low?If the temperature is too high, either decrease the amount of calcium chloride, add more baking soda, or a combination of both. If the temperature is too low, either increase the amount of calcium chloride, add less baking soda, or a combination of both.
Question to investigate
About how much calcium chloride, baking soda, and water should be mixed to reach the right temperature to incubate snake eggs?
You will need
Procedure
Swirl the cup to mix these dry ingredients as well as you can.
Expected results
There should be bubbling as the gas is produced. The temperature should increase and students should be able to get within the target range of 28-32 °C.
Ask students
About how much calcium chloride, baking soda, and water should be mixed to reach the right temperature range to incubate snake eggs?Results will vary depending on the particular calcium chloride and baking soda you are using, accuracy of measuring tools and student measuring technique.
Step 7Have students conduct their chemical reaction in a sealed bag as a prototype heat pack.
Remind students that their challenge is to make a heat pack to warm and safely transport snake eggs. Explain that next they will conduct the chemical reaction in a sealed bag to see if the temperature and amount of gas produced will do the job. Would the chemical reaction you tested in this lesson work if it were sealed in a plastic bag?
Sealing the chemicals in a plastic bag would mean that you would be able to bring just the portable reptile egg incubator with you rather than carry all the supplies needed for each of your tests. In this activity, students combine calcium chloride and baking soda in a zip-closing plastic bag to see if this design will keep reptile eggs warm.
Question to investigate
Does enough heat transfer through the bag to reach the right temperature range?
You will need
Note: The bag will not inflate fully. By only partially inflating, the bag will serve as a better cushion and support for the egg.
Procedure
Combine chemicals in a cup
Prepare the bag
Start the chemical reaction
Expected results
There should be bubbling as the gas is produced and the bag inflates a bit. The bag should feel warm on the surface where the reaction is taking place and should get up to about 28-32 °C. If the outside of the bag does not get hot enough, students can do the reaction again with more calcium chloride.
Ask students
Step 8Discuss features of a portable snake egg incubator that could maintain the temperature for as long as possible and keep eggs properly positioned.
The lesson, so far, has focused on a chemical reaction which would reach a temperature to keep one snake egg warm, but not too warm. Students will need to think of a way or ways they could keep the heat generated in the chemical reaction around the egg during the time it is transported. Once the chemical reaction is over, it will no longer generate heat. So, students will need to consider using some sort of insulation in their device.
Because reptile eggs must remain in the position they are found, the device should ensure that the egg is not turned or jostled too much. Perhaps the partially inflated bag students experimented with could be used to hold the eggs in position. Help students think about how they might build their snake egg protection device.
Ask students
Have each student or group design a model snake egg protection device.Students will draw their device and answer the following questions:
The story below concludes the lesson. Students will find the same story on the last page of their student activity sheet.
Reptiles rescued!
Congratulations, your device works! It was used to take the snake eggs from the construction site safely to the reptile conservation center. The eggs were carefully placed in incubators and both the temperature and humidity were ideal for the growth of healthy snakes.
Because most reptiles can feed and take care of themselves as soon as they hatch, the baby snakes will be taken to a new location and released into the wild. There they will make their new home as they strive to survive and thrive.
What is the 5-E format?The 5-E instructional model is an approach to teaching and learning that focuses on active engagement, inquiry-based learning, and collaboration.
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Egg Incubation
Crossref Citations
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Snake Eggs Found In Cornwall Hatched In Yoghurt Maker
A family from Cornwall has hatched four grass snakes in a yogurt maker after finding eggs in their garden.
Tim Fuge, from Tremar, near Liskeard, said he accidentally unearthed 10 eggs in his compost heap about six weeks ago.
In an effort to save them, he then incubated them in a yoghurt maker and researched how to care for them with his son.
He said four of the eggs had hatched so far and there were six to go.
They were incubated in a yogurt maker
Mr Fuge said he and his son had become fascinated by the process of rearing them.
He said the snakes were about the size of a pencil after they first hatched two days ago.
"The obsession with watching them hatch has been very unproductive over the last few days," he said.
"It's been fun learning about it ... Having to make sure we're keeping them the right temperature, the right humidity all the time, has been a really great experience."
The family has started releasing the baby snakes close to where they found them.
Gary Powell, from the Amphibian and Reptile Conservation Trust wildlife charity, said handling snake eggs was a delicate process.
He said: "Well done for saving the animals after accidentally disturbing them, but we don't recommend people do it because they are fragile and it's not a straightforward process."
The eggs started to hatch two days ago
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