As part of the lab protocol, students first learned a simple titration technique and determined the relative vitamin C concentration of different orange juice preparations. After completing the introductory component of the investigation, (see Part A of the Vitamin C Analysis) students were asked to share some questions they had regarding vitamin C concentrations in foods. In cooperative groups of two, students next designed a scientifically controlled experiment to answer one of their questions; they conducted the experiment, collected data, and reached a conclusion based on their findings. They were then required to share their protocol and findings with the class. At the conclusion of each presentation, students listening to the reports were expected to make "warm" and "cool" comments about the experimental procedure and also the presentation. Students were expected to be both active listeners and participants. At specific key points during the vitamin C investigation, students were asked to search the literature for additional vitamin/enzyme information.

A 5E approach was used in teaching this activity. The steps utilized are outlined below:

Discussion is the first step of the 5E approach where students are given some motivation to learn about the topic and to determine the students’ current level of understanding.

The following are some questions students were asked to discuss in pairs before starting the lab. After they recorded their ides, they were then asked to pair with another group to compare and discuss their respective responses. One member of each group of four was then asked to report to the class.

Questions:

• Why are vitamins important?
• Do any of you take vitamins? Which ones? Why?
• What might happen if you didn’t have enough of a certain vitamin in your diet?
• Can you overdose on vitamins?
• How do we know how much is enough?
• After discussing their answers to the questions, students were then told the following "story."

Two hundred years ago, men setting out on a long sea voyage had a 50% chance of returning. The main cause of death was not pirates, sharks, or being washed overboard. It was to a disease called scurvy. Just to give you an idea of numbers, records show that some time during the 1740s, a crew of 400 British sailors was reduced to 200 primarily as a result of scurvy.

Approximately 250 years ago a British physician set out to learn what caused scurvy. He described the symptoms of the disease as follows: large, discolored spots over the body, "swelled" legs, "putrid" gums, no energy, ulcers on legs, rotten bones, and fungus flesh. One of the more fascinating symptoms he related is that old scars would break open just as if the wound had recently been inflicted. He also reported that people with scurvy could eat and drink well but, because they had no energy, they would stay in bed all day. If called out of bed, they would attempt to stand and the bones in their legs would break. In an attempt to learn the cause of scurvy, the physician designed a controlled, scientific experiment. He selected one group of sailors to eat as usual. Then he established five other groups that each day ingested the following: (1) sea water (2) vinegar (3) sulfuric acid (4) oranges (5) lemons. Those consuming the citrus fruit did not develop the symptoms of scurvy. Scurvy was found to be caused by a dietary deficiency of vitamin C.

Using this information, each British sailor consumed a daily ration of lime juice to prevent scurvy. Hence, British sailors became known as "limeys."

This is step two of the 5E approach. Students explore some aspect of the topic.

This is step three of the 5E approach. Students interpret their findings and share their experiences.

This is step four of the 5E approach. Students have the opportunity to probe more deeply into the topic applying skills and learning from previous experiences.

Using Part B of the Vitamin Analysis, students designed an experiment to demonstrate the effect of various factors on vitamin C levels. Some things they could opt to investigate were:

1. Determine the effect of pH on vitamin C content of orange juice.  Things to consider if you choose this experiment:

1. How are you going to have a control in this experiment?
2. What type of acid/base will you use?
3. How much acid/base will you add to how much juice? Does it matter?
4. What information needs to be recorded?
5. Are there other factors you need to consider?

2. Determine the effect of light on the vitamin C content of orange juice.   Things to consider if you choose this experiment:

1. How you are going to vary the amount of light to which the juice is exposed?
2. What will you use for your light source?
3. For how long are you going to expose the juice?
4. What information needs to be recorded
5. Are there other factors you need to consider?

3. Determine the vitamin C content of assorted vegetables and fruits.  Things to consider if you choose this experiment:

1. How are you going to convert solid fruits and vegetables into liquids?
2. How can you standardize these preparations??
3. What information needs to be recorded?

4. Determine the effect of heat processing on the vitamin C content of foods.   Things to consider if you choose this experiment:

1. Are you going to use processed foods or process your own?
2. If you process your own, how are you going to prepare and treat the samples?
3. What safety measures need to be considered?
4. What information needs to be recorded?

5. Perform a cost analysis to find out which orange juice is most economical, based on its vitamin C content.

This is step five of the 5E approach. Students formalize their new knowledge through a written report, oral presentation, and/or laboratory performance.

Students:

• wrote a formal lab report as described in Part B of Vitamin C Analysis
• completed the Performance Assessment.
• presented their findings to the class on posters, in brochures, or PowerPoint slide shows.
• created a food product label for an orange.
• did a library/web search and wrote an essay describing another vitamin deficiency disease. They had to include the name of the vitamin, symptoms, where it was and perhaps is still a problem, who discovered the cause of the disease and when.

It should be noted that students were provided with the appropriate