Thermal+PBL

=Problem-based learning: Chocolate Melting Day @ HCI= = = = = = = = Results of Solar Heating Melting Points =

= Introduction = Have you seen a chocolate melter?

This action PBL requires a chocolate lover like you (we all are, right?) to **// design and build a solar chocolate melter //**. In week 8, on chocolate melting day, all teams will have to bring their solar chocolate melter to school and compete for the **// "most effective chocolate melter" //** award.

= The Problem = You will have to decide on a container-tin can, cardboard box, plastic bucket, paper bag, or similar object-to use as a solar cooker. Then consider how to melt a refrigerated standard-size milk chocolate chip that has been placed on the end of a toothpick inside the cooker in as short a time as possible.

This includes figuring out how to reshape the container so that the heat energy from the sun is concentrated on the chocolate chip, deciding what colors and textures to use for lining inside surfaces and insulating the cooker, examining where to put the chocolate chip, and identifying how to point the cooker at the sun.

Reviewing scientific information helps you improve the effectiveness of their cooker designs and make predictions about the ones they think will cook the most rapidly. On **Chocolate Melting Day @HCI**​, teams will collect and record data to share with other students doing this problem.

= Designing, Building and Testing your Chocolate Melter = > Remember you want to concentrate sunlight on a chocolate chip that is placed on the end of a toothpick.
 * Designing Your Cooker**
 * 1) Look carefully at some of these solar oven designs and try to figure out what makes them cook food quickly.
 * 1) Use the questions below to help you design your solar cooker.
 * What material will you use to let sunlight shine into your cooker?
 * What can you use to line the inside surfaces of the cooker?
 * What can you do to hold the heat energy inside the cooker?
 * How will you point your cooker to catch the sun's rays?
 * How will you hold the toothpick and chocolate chip in place?


 * Keep the Procedures of chocolate melting day in mind**

__Procedure for Chocolate Melting Day__
 * The chocolate chips will be in the refrigerator for at least an hour before putting them in your solar cooker. If you'll be working outside in the hot sun, be sure to keep the chips cool. To do so, move them from the refrigerator into a cooler with a cool-pack or fill a can or unbreakable cup with ice, put a layer of paper towel over the ice, and lay the refrigerated chocolate chips on top. (Remember to keep the chips cool, not frozen. A frozen chocolate chip will break when pierced with a toothpick.)
 * Take your solar cooker and data logger for measuring the temperature of the air inside it to a shady spot. Put the large end of a standard-size refrigerated milk-chocolate chip on the end of a toothpick. (If the chip is wet, use a paper towel to wipe it dry. Also, be sure to have a few paper towels or napkins handy for cleaning melted chocolate from your fingers.)
 * Carry your cooker to a testing site, position it in the sun, and record the time you started melting the chocolate chip. Place the temperature data-logger next to your cooker.
 * Watch the shape, color, and shininess of the chip. As soon as you think it is fully melted, record the time and the temperature of the air outside of the cooker. Remove the toothpick and chip immediately from the cooker. Test to see that it is fully melted by squishing it between thumb and forefinger. If you find the chip is not completely melted, take your cooker to a shady spot and start over.
 * To calculate the time it took to melt the chocolate chip subtract the time you started melting the chip from the time you stopped melting it.
 * Test, redesign, and test your cooker as often as you'd like.
 * Be sure to clean everything up before you leave the test site.

Things to Try:
 * Try some of these things**
 * Different size and/or shaped containers.
 * Different textured materials for lining the cooker.
 * Different colored materials for lining the cooker.
 * Different ways of insulating the cooker.
 * Chaging the shape of the inside surfaces
 * Changing the location or angle of the toothpick.
 * Different ways of pointing the cooker at the sun.
 * Change one thing at a time to see what works best.

= How much Time is Given? = Week 8 -- Chocolate Melting Day@ HCI, Tue (Trial) Thur (Full Run) Week 9 (Thur) Submit report on wiki (Will not limit the min. no of pages) **
 * Week 3 (Thursday) - discussion session

=Rubrics= This problem will assessed based on a total of 285 points.

//The melter that holds is most effective will receive 150 points. All other teams will receive a score based on their melter's timing held as a percentage of the most effective chocolate melter.//
 * Time taken to melt chocolate chip fully ........................................ 80 to 150 points**

Appearance of melter .................................................................. 0 to 5 points**
 * Creativity of melter ...................................................................... 0 to 20 points

Design Report //In your report, please include:// Application of Physics concepts ........................................................80 points Information (pictures/videos/graphs) on trials and design iterations ............20 points** should include at least one trial and one design modification // **What did you predict?** What did you do? What did you learn and how did you modify your design after the trial? // **Please include Reflection (short description on your personal feelings/lessons learnt for this project)**
 * Design features ................................................................................10 points
 * What data did you collect?**

= Size of chocolate chip = On the beautiful Saturday, at 11am, my chocolate chip from the freezer took 1 h 15 min to melt.... videos coming up.... Regarding the size......you already have a sample....

= FAQ** =

> NO. > What do you think? of course .....NO > >
 * 1) Can the chocolate chip be titled such that it touches the base of the melter or any surface?
 * 1) Can I use a solar cell?