Lesson Plan

Summary: Students work in teams of four as they conduct four controlled Jell-O experiments over a two-day period. Styrofoam, sugar, salt, and room temperature treatments are compared to control Jell-O to investigate the effect of these treatments on the phase change of Jell-O from liquid to solid (freezing point). The Take It Further section explores the environmental pros and cons of using salt (one of the Jell-O treatments) to improve roadway safety. The Family Page extends this learning to the community by providing families with challenges to explore at home.

Talk to your cafeteria supervisor (i.e., borrow trays, ladel, cook pot, walk-in fridge space, etc.).
Organize materials into team trays. Each tray will need:
- box of Jell-O (small)
- mixing bowl (plastic ice cream tubs work well)
- plastic spoon
- measuring cup (50-500ml)
- mini measuring cup or measuring spoon (5ml)
- Styrofoam cup and rubber band
- one straw per person
- two Dixie cups per person
- two markers (to label cups)
Gather the following Whole Class Materials:
- sugar
- salt
- cook pot
- ladel
- thermometer
- refrigerator access
- microwave access
- cold water access
Heat 2500ml (10 cups) of water.
Copy a class set of the Thinksheet, Data Sheet, and Family Page. (See Ready to Print.)
Review Related Resources.

Introduce the activity to your students. "In this activity you will..."
- investigate phase change and density as it relates to Jell-O
- use measurement skills to make Jell-O in teams
- hypothesize the effect of a treatment variable (salt, sugar, Styrofoam cup, or room temperature) on the phase change of Jell-O
- conduct Jell-O testing (and eventually eating!)
Review/Introduce the terms treatment, control, and phase change. (See Background Information.)
Tell students what behaviors you expect of them before, during, and after the lesson.
- scientific thinking
- respectful listening
- speaking in appropriate voices
- participating
Explain how this activity is grouped:
- whole class introduction
- team Jell-O making
- individual Jell-O testing
- whole class discussion
Have students get into teams of four and number off.

Set up the Thinksheet
- Students complete the "Question"section of the Thinksheet by filling in their treatment (#1: room temp., #2: salt, #3: styrofoam, #4: sugar).
- Under "Think it Through," give students one minute to list what they know about Jell-O.
- Call on three or more students to share their responses.
- Give students one minute to list what they know about their treatment.
- Call on three or more students to share their responses.
- Remind students to be thinking about how their treatment might affect the phase change of Jell-O.

Explain that each student will be making two cups of Jell-O (one control, one treatment).
Distribute trays of materials.
#1: Read the directions for Jell-O on the box aloud to the team.
#2: Read the directions for Jell-O on the box aloud to the team AGAIN.
#3: Have students mark their cups with their last names. One cup should be marked "C" (for control) and the other "T" (for treatment).
#4: Use measuring cup to get 250ml (1 cup) of hot water FROM THE TEACHER. Add it to the mixing bowl.
#1: Add Jell-O mix to the bowl.
#2: Stir the hot water and Jell-O mix until dissolved.
#3: Add 250ml (1 cup) of cold water.
#4: Final stirring.
Verify that all teams are ready to continue.

Preparing the Control and Treatment Cups

Students measure 50ml of Jell-O into each of the eight team cups.
Demonstrate how to package the Styrofoam treatment.
#2 and #4 add salt and sugar treatments to the appropriate treatment cups (10cc recommended). Stir well.

Place trays in refrigerator. DON'T FORGET TO LEAVE OUT THE ROOM TEMPERATURE TREATMENT CUPS!
**Note: If possible, put Jell-O in the freezer for the first 10 minutes to speed cooling.
Record initial observations on Data Sheets and discuss.
Conduct straw tests after 10-20 minutes of refrigeration. Record results and discuss findings.
Place Jell-O in the fridge until tomorrow.

Day 2: Jell-O Testing, Eating, and Class Discussion (45 min.)

Conduct straw tests. Record results and discuss findings.
Demonstrate how to find the melting point of Jell-O.
- Insert a straw in the middle of a cup of control Jell-O so it is standing upright.
- Place the Jell-O in a microwave on defrost for 5-10 second intervals until the straw falls over.
- Remove the Jell-O and check the temperature with a thermometer to find the melting point.

Take It Further!

Check out Related Resources.
Investigate the pros and cons of using salt to improve roadway safety in the winter. (See Related Resources.)
Have students complete a rough draft of the Thinksheet and Data Sheet in their science spirals and then write a final copy using the supplied sheets for their portfolios.
Allow students to create their own graphic organizers for data.
Use a Venn Diagram as a data organizer instead of or in addition to the Data Sheet provided.
Have students role play Jell-O atoms in groups of eight or so as they go through phase change from liquid (less tightly packed) to solid (more tightly packed). Use the Simon Says... theme as a management tool.
Hypothesize about the parabolic shape of the surface of the control Jell-O after its phase change. Create an experiment to test one or more of these hypotheses. Explanation: The Jell-O cools from the outer edge to the center. As the atoms in the Jell-O phase change, they become more tightly packed and take up less space in the cup. Surface tension on the edges keeps the Jell-O near its original height in the cup. Since there is nothing for the Jell-O to attach to in the center, the increased density of solid Jell-O can be observed via the parabolic effect. A similar surface tension phenomenon can be observed when water droplets are placed one after another onto a penny.