GEMS project

§112.4. Science, Grade 2.b (2) (E) Construct reasonable explanations and draw conclusions using information and prior knowledge
§112.4. Science, Grade 2.b (2) (F) Communicate explanations about investigations
§112.4. Science, Grade 2.b (7) (A) Observe, measure, record, analyze, predict, and illustrate changes in temperature.

CONCEPT STATEMENT:

When ice melts, it absorbs energy, changing water from a solid to a liquid. Using ice to cool the ingredients for ice cream will absorb the energy from the ingredients and the outside environment. That includes one’s hands when holding the bag of ice. Rock salt can be added to lower the freezing point of the ice, making the ice colder than before. This is how the ice cream freezes. http://chemistry.about.com/cs/howtos/a/aa020404a.htm

PERFORMANCE OBJECTIVES:

Students will be able to:
*Compare the temperature differences between the mixture of plain ice and ice with rock salt.
* Identify the ingredient that will cause colder temperatures for freezing ice cream.

RESOURCES:

For the Class:

•   1 bag of ice cubes or crushed ice, about 5 lbs.
•   Access to a nearby freezer or cooler to store ice
•   3lbs. rock salt (about 4 cups)
•   1 black permanent felt marker
•   1 ziplock sandwich bag
•   Your own personal cup from previous sessions
•   3 color coded plastic sups (one each: blue dot, green dot, orange dot)
•   3 oz. regular milk
•   1/2 cup white sugar
•   1/2 cup vanilla extract (about 1 oz.)
•   1/2 cup strawberry extract (about 1 oz.)
•   1 roll of plastic wrap
•   1 small, lightweight plastic spoon
•   1 popsicle stick
•   1 plastic stirrer
•   2 droppers
•   3 squeeze bottles of food coloring(red, yellow, blue)
•   1 8 piece of 8 1/2” x 11” white construction paper
•   3 dots (blue, green, orange) for the color key
•   1 dump bucket or access to a sink
•   1 piece of butcher paper or chalkboard

For the Class:

•   1 cafeteria tray
•   3 plastic cups (1 red dot, 1 yellow dot, 1 green half-dot)
•   1 small, lightweight plastic spoon
•   1 popsicle stick
•   2 ziplock sandwich bags

SAFETY CONSIDERATIONS: Emphasize that students should not taste the rock salt. Student should also be careful not to touch their eyes while handling the rock salt, as it may cause stinging. If they should get salt in their eyes, they should immediately rinse with water. Though students will not be making their ice cream in this session, sensitivity should be taken towards food ingredients as you prepare for the next sessions. Some students may have some dietary restrictions, such as milk allergies. When making ice cream, milk can be substituted with mocha mix or other soy or rice based drinks. Special consideration should also be taken for sugar with some students. If any student has any allergic reaction, they should inform the teacher immediately.

SUPLEMENTARY MATERIALS, HANDOUTS: Gems Guide Secret Formula Session Eight pages 79-86 for teacher only. This will be needed for exact break down of instructions. Ice Cream Formula data sheet (last page in book) will be used on overhead projector as the ingredients that will be used to make their ice cream are introduced.

ENGAGEMENT		Time: __5 minutes______
What the Teacher Will Do	Probing Questions	Student ResponsesPotential Misconceptions
Students will first be engaged by introducing they will be making their own secret formula ice cream in the next session. There will be a discussion about homemade ice cream and ways students may have made it.	Think about and describe the attributes of ice cream. What do you like about ice cream?	Sweet, cold, flavors, etc.
Teacher will model how the students will add the ingredients by going through the Ice Cream Formula data sheet on the overhead projector and doing a small demonstration. (See Gems Guide for proper steps)	As the students refer to the number of drops or spoons on the data sheet, ask, “What is the most you can use?” Once ingredients are mixed, holding up bag, ask, “Is this ice cream?” How do you make ice cream cold?	Five spoons sugar, four drops vanilla, etc. No! It isn’t cold or hard. Many students will say ice. Clarify that the ice isn’t an ingredient--it doesn’t go in the ice cream. It goes near it to make it cold.

EXPLORATION

Time: __10 minutes______

What the Teacher Will Do

Probing Questions

Student ResponsesPotential Misconceptions

Introduce rock salt and ice. (See Gems Guide for proper steps)

What did you feel when you touched the plain ice and the ice with rock salt?

I want you to vote on which cup you thought was colder. Which would be better to use for making ice cream?

Cold.

Rock salt. If some students are not sure, that is all right. The next test will be more conclusive.

EXPLANATION		Time: ___20_____
What the Teacher Will Do	Probing Questions	Student ResponsesPotential Misconceptions
Have the students conduct the freeze test. (See Gems Guide for proper steps)	What might happen to the water in the bags?	It might freeze.
Explain it takes time for things to freeze, so they are going to let the ice cups sit while they listen to a story (“Brr! By James Stevenson).
After about 10 minutes, remind them the goal is to find out how they can best make their ice cream cold. Explain that by observing what happened to the water, they may find out.	What did you see? What happened to the water in your bags? What should you use when you want to freeze your bag of ice cream?	Water is colder, more solid. Frozen. Ice and rock salt.

ELABORATION

Time: ____10____

What the Teacher Will Do

Probing Questions

Student ResponsesPotential Misconceptions

The teacher may let the students look at temperature in more detail by using a thermometer to measure and then record the temperatures of both the ice and the ice with the rock salt (and feel with fingers).

What were the temperatures of each cup? What does the graph show?

Students can create graphs with their measurements.

Bar graph - The lower bar indicates the cup with ice and rock salt was colder.

EVALUATION		Time: ____during____
What the Teacher Will Do	Probing Questions	Student ResponsesPotential Misconceptions
Students will be evaluated throughout the experiment to determine if they conducted the investigation properly to determine how to best freeze ice cream.	The questions which are asked throughout the experiment are being used as part of the evaluation.	Student responses and misconceptions are stated above.
Students will also be evaluated during the next lesson, where they will be creating their last secret formula of the unit to make ice cream (culminating activity and overall mastery).