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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?

Small and light-weight

Uses small amounts of chemicals

Gets to the right temperature and stays there long enough

Can help support and protect the egg

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 chemicals might not produce the right temperature

Might need a large amount of chemicals to make it work (too expensive and wasteful)

The temperature might not stay in the right range long enough

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

Do these eggs belong to a snake, turtle, or lizard? Snake

How do you know? Both lizard and snake eggs are laid on top of the ground, but snake eggs are larger.

What temperature range should you aim for when you develop your heat pack? 28-32 °C

Step 5Have students begin developing their device by dissolving different amounts of calcium chloride in water.

Ask students

Do you know of a chemical that gets hot when dissolved in water? If students have done the activities in Chapter 5, they may remember that dissolving calcium chloride in water causes an increase in temperature.

How can you design a test to see if the amount of calcium chloride dissolved in water affects the temperature change? Use the same amount of water but add different amounts of calcium chloride to see which causes the greater increase in temperature.

Question to Investigate

Does the amount of calcium chloride dissolved in water affect the temperature change?

You will need:

Goggles

2 small thermometers

Calcium chloride

Baking soda (used in the second part of the procedure)

Water

2 small clear plastic cups

1 graduated cylinder, medicine cup, or Tablespoon

Measuring spoons (⅛ tsp., ¼ tsp. And ½ tsp.)

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

Pour 15 mL of water into each of two small clear plastic cups.

Place a small thermometer in each cup and record the initial temperature.

With the help of a partner and at the same time, add ¼ tsp. Of calcium chloride to one cup and ½ tsp. Of calcium chloride to the other cup.

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

Calcium chloride seems like it might be a good chemical for the heating part of the heat pack design, but what about the need to cushion and protect the egg? Is there something we could do to make the heat pack puffy? Yes. Another substance could be added so the reaction also produces a gas. Production of the right amount of gas could make the heat pack into a little pillow which could cushion and protect the egg. But if too much gas is produced, the pack could pop or be too big to work well.

What do you think you could add to the calcium chloride solution to produce a gas? Baking soda. In Chapter 6, Lesson 7, students added calcium chloride to a baking soda solution and saw it bubble. They could reasonably think that adding baking soda to a calcium chloride solution will do the same thing.

Add baking soda

Add about ⅛ teaspoon of baking soda to the solution that reached the highest temperature. Watch the solution and the thermometer.

With the thermometer still in the cup, gently swirl and check the temperature. Record the lowest final temperature reached.

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

Calcium chloride

Baking soda

Measuring spoons (⅛ tsp. And ½ tsp.)

2 small clear plastic cups

Water

Thermometer

Procedure

Place ½ tsp. Of calcium chloride in a cup.

To the same cup, add ⅛ tsp. Of baking soda.

Swirl the cup to mix these dry ingredients as well as you can.

In a separate cup, add 15 milliliters of water, place a thermometer in the cup, and record the temperature.

With the thermometer in the cup, add all the calcium chloride and baking soda mixture and gently swirl to mix.

Record the final temperature in the chart on the student activity sheet.

Adjust the amount of calcium chloride and/or baking soda and try the reaction two more times to achieve the target temperature.

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

Calcium chloride

Baking soda

Measuring spoons (⅛ tsp. And ½ tsp.)

Graduated cylinder

2 small clear plastic cups

Small zip-closing plastic bag

Water

Thermometer

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

Place the amount of calcium chloride and baking soda, which resulted in the best temperature from the previous procedure, in a cup.

Swirl the cup to mix these two dry ingredients.

Prepare the bag

Pour the combined powders into one corner of a small zip-closing plastic bag. Tilt the bag so that all the calcium chloride and baking soda stays in one corner.

Use your fingers to seal off that part of the bag.

Have your partner pour 15 milliliters water into the other corner of the bag so that the water does not touch the dry powders.

While keeping the water and powders separated, try to get the air out of the bag as you close it and make sure that it is tightly sealed.

Start the chemical reaction

Let go of the corner and tilt the bag so that the water and the powders mix and react.

Position a thermometer under the bag so that the bulb is beneath the solution where the chemical reaction is taking place. Be sure you can read the temperature without having to remove the thermometer. Record the highest temperature reached in the chart on the activity sheet.

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

Since the plastic bag will be part of the portable egg incubator, enough heat needs to transfer through the bag to the egg. Does enough heat transfer through the bag to warm a snake egg enough?Yes.

The bag inflates slightly. How could this feature be useful in the design of the portable egg incubator?If we place the bag under, around, or on top of the egg, it may be able to hold the egg in place so that it is not flipped, turned, or jostled when it is being transported.

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

How will you incorporate the partially inflated bag so that the egg is supported? The bag could be placed in a paper, plastic, or Styrofoam cup so that the bottom of the bag would be insulated, and the egg could be placed on top of the bag in the cup.

What are some ways you could keep the egg and the inflated bag warm for as long as possible?The container that the bag and egg are placed in will insulate to a certain extent. Perhaps torn paper, paper towels, or a lid could keep the egg warm for a longer time.

Have each student or group design a model snake egg protection device.Students will draw their device and answer the following questions:

How does your device keep an egg at the ideal temperature for as long as possible? 

How does your device hold an egg in the proper orientation? 

How does your device protect an egg from impact?

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.

Learn More

Egg Incubation

Crossref Citations

This Book has been cited by the following publications. This list is generated based on data provided by Crossref.

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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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