Darling Engineers

On a cold winter day in Waterville, Maine, Laurette Darling tells her fourth graders they will be designing and constructing features of chocolate melting solar warmers. During melter design work no longer are they students, Mrs. Darling tells them. Instead they are engineers who, like professional engineers will use given criteria and deal with constraints as they create their solar chocolate melters. The class becomes transformed from Mrs. Darling’s fourth grade class to the Darling Engineer firm.

The class had just listened to the story Lerato Cooks Up a Plan. In the book Lerato, a girl about the fourth graders’ age who lives in Botswana, feels discouraged about her future ability to be a college student because she finds it difficult fulfilling her current responsibility, taking care of her young siblings. But when Lerato and her siblings design an insulation system for a solar oven, Lerato begins to realize  – yes, it would be possible for her to succeed at college. With their own possibilities stirred by Lerato’s life and engineering accomplishment, the children begin their engineering challenge.

Connecting to Prior Knowledge and Generating Questions

Since Mrs. Darling’s students already have been studying properties of the sun they are aware of it as an energy source. Using an informational picture book, Earth and Sun, teacher presentations, peer collaboration, class discussion, note-taking and videos, fourth graders at Albert S. Hall School (ASHS) have been addressing a State of Maine Science and Technology Standard: “Recognize that the sun is the source of the Earth’s surface heat and light energy.”  That understanding will be deepened and put to use, as students use inquiry and research to design and construct their solar melters. HPIM2117

Individually, in their notebooks and then in a class discussion, students respond to “What do you think you know about creating a solar melter?” They then list questions for which they would need to find answers in order to design and build solar melters.

Outside Expert

To understand the real world work of engineers – and further heighten students’ interest in the unit – an engineer guest speaker, Mrs. Darling’s husband, Richard Darling, comes to the class to talk with the children. Mr. Darling explains the work of an engineer and how to use an engineering process to design useful products.


To effectively create and test solar melters, students need to understand equipment and properties of materials they will use. In partners, with Mrs. Darling’s guidance, students handle and read thermometers to learn how to accurately read one, while Mrs. Darling leads a discussion about how thermometers work.

Mrs. Darling reminds students how to use careful measurement and make notes of data they collect. To help them organize their data, students copy the outline of charts Mrs. Darling shows them into their science notebooks, and fill in the charts with their findings.

Reasoning, Individual Work and Collaboration 

Materials available for constructing the melters include newspapers, felt, wool, aluminum foil, plain paper of different colors, and paper cups. Students need to test different materials for their heat conducting and absorption capacity. Working in partners students test different materials wrapped around an ice cube to see if there are differences among them in heat absorption. Students also measure temperatures of the same material in different colors to see if different colors absorb different amounts of heat. Students record their findings in their science notebooks, and the class discusses the concept of insulation.

Now it’s time to begin designing the solar melters. Informed by their findings on different materials’ abilities to absorb heat, students discuss possible solar melter designs with their partners.

Mrs. Darling: “Use your data!  It doesn’t matter that you like purple because it’s a team color.”

Individually, in their science notebooks, students sketch their design that shows a cup wrapped and lined in particular materials and colors. Some designs have a lid on top of the cup, and some heater designs are lidless. HPIM2066Partners discuss and make note of the reasoning behind their choices of design elements. Using best features from the two designs, the partners create a design for the solar melter they will construct – and then begin to build their melter.

Ryan: “We each drew different designs. I drew black felt on the outside and tin foil on the inside. Then me and Maggie came up with a new idea together. We were going to use tin foil all over the cup but then we decided not to because the sun would hit it and then go away.”

Maggie: “We asked another group what they did for the outside because we decided the tin foil completely covering the outside wouldn’t work.” HPIM2080

Ryan:  “But then we figured out if we put felt on the inside it could be better. I went to the window to see if the tin foil would make the reflection of the sun go into the cup.”

Maggie: “We tested various materials to see how well they work in melting ice. We made a box out of yellow foam, batting, coffee filter, tin foil, gray wool, felt, construction paper, and newspaper.  Also we tried the ice cube alone to see how fast it melted.”

Next the class needs to determine the best place to put the solar melters. Should the solar heaters be placed on the window sill? Or outside? If outside, where outside? Again, decision-making is based on data.

Mrs. Darling: “For claims, use evidence/data, for example highest temperature was 120 degrees at 11:00.”          HPIM2135

Students observe different locations at different times of the day to determine how much sun or shade particular locations get. They chart the temperatures of spots throughout the day. The conclusion is the spot sunniest for the longest amount of time (and that can be safely protected) is outside against the wall of the north side of the building.


Once the solar melters, with chocolate pieces inside, are in their sunny location, more scientific process follows. Students go outside to observe whether chocolate is melting in their melter – and if so, how much? They also observe to what extent chocolate melts in classmates’ solar melters.

In their science notebooks, students make a series of sketches over time to depict progress or not of their chocolate melting. In students’ science notebooks students write categories provided by Mrs. Darling and make notes for each category.


Description of Chocolate:HPIM2133

Our Design Worked:

Our Design Didn’t Work:

Our Redesign Will Be:

Maggie and Ryan write in their notebooks:  “Our design worked because we put yellow foam on the outside. We put it there because it made the ice cube melt. We put batting on the inside because it goes in quilts.”

Ryan:  “At 8:15 AM we thought it wouldn’t melt cause temperature was at 70 degrees.  But at 10:00 temperature went to 100 degrees. Then we knew it would melt more. But then it went to 120 degrees at 11:45! At 2:00 temperature went down to 80 degrees because the building it was near created shade. Our design worked but we know it could have been even more effective because Hannah and Noah’s solar melter melted the chocolate more.”

Mrs. Darling: “What surprised you about the results of your solar melter?”

Emily: “Our temperature went up to 128 degrees.”

Abigail: “I am surprised ours didn’t work.” Mrs. Darling: “What is the evidence that it didn’t work?”

Noah and Hannah wrote in their notebooks:  “We are surprised and disappointed because at first the chocolate started to look shiny so we knew something was happening but after that nothing happened. Our highest temperature was 83 degrees.”

Revision and Presentation

Based on how well chocolate melts in their solar melter in comparison to other pairs’ solar melters, partners analyze design factors that make the difference. With this information in mind, partners then have the opportunity to construct a redesigned solar melter and try it out.

Mrs. Darling: “Today, after meeting with your partner, draw and label your redesign.”

Students write in their science notebooks and present to the class why they designed their solar melters as they did. Those who redesigned their melters also explain the reasoning behind the adjustments.

Hannah: “We will put black felt on the outside and insulation on the inside.”

Caleb: “I used to think the tin foil on the outside and batting in the inside would work, but then we realized the tin foil on the outside would reflect the heat away.”

Abigail: “So for our redesign we will put batting on the inside and on the outside black felt.” HPIM2094 - Version 3

Maggie: “We did the same thing as Abigail and Emma. But we didn’t have tin foil in the collar area. We had it as a flap. Our box was also darker.”

Debrief and Celebration    

Finally, students and Mrs. Darling look back on all the students have learned and accomplished, share additional thoughts and questions –  and celebrate their efforts with a chocolate treat!


Teacher Leadership, Teamwork, and Beyond School Connecting

All the fourth grade classrooms at Albert S. Hall School partake in the solar chocolate melter unit. Teachers share resources and connect with each other on the unit’s successes, challenges, and adjustments.

At Albert S. Hall School, teachers lead grade level curriculum areas. A few years ago, Albert S. Hall School science curriculum leaders Laurette Darling and Mary Dunn won a Maine Science Alliance $500 grant to pilot a science unit, which led to the Solar Chocolate Melter unit. A grant stipulation was that the unit uses both science notebooks and engineering. With grant funds, all the Albert S. Hall School fourth grade teachers received books and materials from Engineering is Elementary (Boston Museum of Science).


Planning Information

Unit’s Duration

The Solar Chocolate Melter unit usually takes place during four, 45 minute periods each week, for five weeks.

Standards Addressed

Maine Department of Education Guiding Principles Standards

A. Clear and Effective Communicator:
Understands the attributes and techniques that positively impact constructing and conveying meaning for a variety of purposes and through a variety of modes.

B. Self-Directed and Lifelong Learner: Understands the importance of embracing and nurturing a growth mindset.

C. Creative and Practical Problem Solver : Is skilled at selecting and applying a process of problem-solving to deepen understanding and determine whether redefining the goal is a better way of addressing a problem situation and continuing to consider other alternative solutions until one resonates as the best one.

D. Responsible and Involved Citizen: Understands the interdependence within and across systems and brings to each situation the appropriate actions.

E. Integrative and Informed Thinker: Is skilled at using complex reasoning processes to make meaning.

Next Generation Science

Standard: 4- Energy PS3-3. Apply scientific ideas to design, test, and refine a device that converts energy from one form to another… passive solar heater that converts light into heat. Examples of constraints could include the materials, cost, or time to design the device.

Maine Department of Education Science and Technology

Constancy and Change,Grades 3-5. Make tables or graphs to represent changes.

Skills and Traits of Scientific Inquiry, Grades 3-5. Students plan, conduct, analyze data from and communicate results of investigations, including fair tests.

Skills and Traits of Technological Design, Grades 3-5. Students use a design process, simple tools, and a variety of materials to solve a problem or create a product, recognizing the constraints that need to be considered.

Understandings About Science and Technology, Grades 3-5. Students describe why people use science and technology and how scientists and engineers work. Describe how engineers seek solutions to problems through the design and production of products.

Universe and Solar System, Grades 3-5. Recognize that the sun is the source of Earth’s surface heat and light energy.


Common Core State Standards – English/Language Arts

ReadingLiterature and Informational Texts
Refer to details and examples in a text when explaining what the text says explicitly and when drawing inferences from the text.

Provide reasons that are supported by facts and details. HPIM2134

Speaking and Listening
Engage effectively in a range of collaborative discussions (one-on-one, in groups, and teacher led) with diverse partners on grade 4 topics and texts, building on others’ ideas and expressing their own clearly.
Report on a topic or text, tell a story, or recount an experience in an organized manner, using appropriate facts and relevant, descriptive details to support main ideas or themes; speak clearly at an understandable pace.

Use knowledge of language and its conventions when writing, speaking, reading, or listening.

Formative Assessments/Evaluation of Students’ Progress on Standards

. Students’ notebooks
. Students’ comments
. Observation of students discussing, working, and their presentations of their designs and re-designs
. Students’ solar chocolate melters
. Students’ analysis of their design decisions


Engineering is Elementary Team (2011). Lerato Cooks Up a Plan. Boston, MA: Museum of Science

Kalman, B. (2008). Earth and Sun. New York, NY: Crabtree Publishing

Engineering is Elementary, Boston Museum of Science (2015). Energy: Now You’re Cooking – Designing Solar Ovens Unit.  http://www.eie.org/eie-curriculum/curriculum-units/now-youre-cooking-designing-solar-ovens

School Demographics and Funding

67% eligibility for free and reduced lunch (USDA Nutrition and Food Services, Oct. 2011)

Classes are inclusive of students identified with special needs.

Per pupil operating costs $8,055.34 (2012-13 data, Maine Department of Education, 2014)


All students’ names have been changed.

Copyright © 2015 Lee Anna Stirling

All Rights Reserved

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