Materials per group:
Dehydrator (1 per class- oven may work on low)
Fruits and vegetables (your choice-many small pieces:6-8 different types cut into small pieces)
balance (1 per class - more if possible)
data sheet and graph paper (1 per student)
plastic storage bags (1 box)
calculator (1 per student or group if possible)
goggles (1 per student)

note: Amounts of material may vary depending on your class size.

Procedure:
Introduction of topic (space) (1-2 class periods)
1. Watch Kids Quest " Fill Your Head With Space”.

2. Cover information in your science text about nutrition.

3. Visit educational web sites about space.
( http://www.pbs.org/teachersource/ )
( http://education.nasa.gov)

4. Review the scientific method in your textbook.

Process:
1. This activity is a perfect lab to use to help students understand the basics of the scientific method. Before the lab begins you could introduce the activity and ask the students to hypothesis which fruits and vegetables have the highest percent of water content. The students could use the steps of the scientific method to prepare a pre-lab investigation. The number of steps completed for the scientific method varies depending on which book you use. Below are some sites which explain the scientific method in detail. Also, you will find an simple example shown below.
http://biology.clc.uc.edu/courses/bio104/sci_meth.htm
http://teacher.nsrl.rochester.edu/phy_labs/AppendixE/AppendixE.html

2. The students need to be placed in-groups of 2-3. They should choose 4 - 6 types of foods. The students should weigh the food they received. They must record the information on a data sheet.

3. The students should place the food in the dehydrator. Make sure each group marks their food when they place it in the dehydrator. A small piece of paper with the group name could be placed by the food. The dehydrator should be left on overnight or whatever time recommendations are on the dehydrator.

4. The food items should be removed from the dehydrator. The food should be placed in a plastic bag to cool. The food items should be weighed on the balance. The information should be recorded on the data sheet.

5. The students should compare the amount of water released for each type of food sample. This should be a % water loss. The % water loss should be used instead of total water loss because comparisons will be more accurate. The equation below can be used to calculate the % water loss. The students will need help with this part of the experiment.

                          weight of original food - weight of dehydrated food
% water loss = ------------------------------------------------------------------------------ X 100%
                                     weight of original food sample

6. The students should graph the data. The students could graph the food type and % water loss. The students should compare the results of the investigation with their pre-lab expectations.

7. The activity can be modified to meet your needs.

(example graph À can be completed on paper)
(does not represent actual data)

State Standards:
If completed correctly, the following standards are used in the activity above. More standards could be used by including spin-offs of the activity. For example, a paper could be written about the history of space food.
State Content Standards

Number indicates standard number

FOURTH GRADE MEASUREMENT STANDARDS - THE STUDENT WILL:
3. select and use the most appropriate units for given measurement situations.
5. explore the use of formulas that assist in measurement situations. (example: area) (example: using % weight loss instead of weight loss)
6. use scales of length, temperature, volume, and weight for problem solving.
9. develop strategies to make measurement estimates. (students could help you come up with the % weight loss equation, also explain why it is better than using simple weight loss)

FOURTH GRADE NUMBER SENSE STANDARDS - THE STUDENT WILL:
5. apply multiplication and division facts through the 12s.
7. find the quotient of two whole numbers.

FOURTH GRADE STATISTICS & PROBABILITY STANDARDS - THE STUDENT WILL:
2. use appropriate scales to represent data in various forms.
3. interpret and analyze data from graphical representations and draw justifiable conclusions.

FOURTH GRADE NATURE OF SCIENCE STANDARDS- STUDENTS WILL:
2. identify characteristics of scientific ways of thinking. (scientific method)
4. explore the scientific process as identifying a problem, developing a hypothesis, experimenting, collecting data, and drawing conclusions.
5. develop questions to formulate hypotheses and use data to make predictions.
6. make distinctions among predictions, observations, and conclusions.
7. use appropriate standard and metric measures to collect, record, and report data in graphical representations.
8. recognize numerical data that are contradictory or unusual in experimental results. (may happen)
9. recognize the effect of manipulated variables on the outcomes of events. (example: same size pieces of food- different sized pieces will affect the results) could show this
10. use appropriate scientific equipment for investigations.
11. use proper safety procedures in all investigations.

FOURTH GRADE PHYSICAL SCIENCE STANDARDS- STUDENTS WILL:
4. differentiate between the states of matter when matter changes. (example: from a solid to liquid) you could describe the water in the food changing from a liquid to a gas

FOURTH GRADE SCIENCE, TECHNOLOGY, ENVIRONMENT, AND SOCIETY STANDARDS- STUDENTS WILL:
2.investigate how new ideas and inventions often affect people. (could study history of food in space and ready to eat meals for soldiers)
4.explain how inventions have changed people's lives. (example: television, electric lights) (example - space food)

Credits:
Resource: South Dakota Department of Education Content Standards