Rotting Fruit (Marissa Staller)


Conservation of Mass in Rotting Fruit


Marissa Staller


1. Which type of fruit rots the fastest? (strawberries, bananas, kiwis, apples, oranges)

2. Will the mass of the reactants at the beginning of the experiment be different from the mass of the products at the end of the experiment?


8th grade, CA Science Standards

5. Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:

5. a. Students know reactant atoms and molecules interact to form products with different chemical properties. 

5. b. Students know the idea of atoms explains the conservation of matter: In chemical reactions the number of atoms stays the same no matter how they are arranged, so their total mass stays the same. 

9. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

a. Plan and conduct a scientific investigation to test a hypothesis

c. Distinguish between variable and controlled parameters in a test

Experimental Design

Students will be measuring the masses of the products and reactants over time in a long-term project. Students will also determine which type of fruit rots the fastest - strawberries, kiwis, apples, or oranges? Students will take measure the mass of each jar of fruit, and take pictures of the rotting fruit each week.

Independent variable

Type of fruit

Dependent variables

Amount of rotting, as measured by the presence of mold and moisture


Compare the masses of each of the jars of rotting fruit each week to determine if the masses have changed at all 


Same type of jar should be used for each fruit, same mass of fruit should be used to start out with


1. Clean plastic peanut butter jars, 12 oz.

2. Fruit - strawberries, bananas, kiwis, apples, oranges, other types of fruit if desired

3. Electronic or triple beam balance

4. Camera


1. Gather all the materials you will need for this project. These include the strawberries, bananas, kiwis, apples, oranges, etc. the clean plastic peanut butter jars, a camera, and the electronic balance.

2. Measure and place 50 g of each fruit in a separate jar. These will be stored at room temperature.

3. Measure the total mass of the jar and the fruit for each type of fruit. Record on data table.

4. Take a picture of each type of fruit. On the computer, label the pictures with "Type of Fruit - Week #". For example, label picture of the strawberries "Strawberries - Week 1".

5. Observe each of the fruit samples on a weekly basis for a period of 8 weeks, recording any changes in temperature, any browning of the skin, discoloration, and any residue of moisture or signs of dehydration.  Record your observations on the weekly observation chart. 

5. Each week, you will be repeating steps 3-5.

6. Review all of your data. Write your final report, answering the research questions. Include your photos, charts of data, a summary of your research, and your bibliography. 

Sample data and graphs

Chart #1: Observations of Changes in Fruit (to be done each week)

Chart #2: Masses of Fruit jars, by week

Photographs and Movies

Rotting Fruit Video


Marissa Staller,
Dec 5, 2011, 10:15 PM