2014 MSU Science Festival Community Experiment

Best Lettuce Experiment

Background

If you are going to grow lettuce at home or in a school garden, what lettuce should you grow? There are hundreds of cultivars to choose from. In the Best Lettuce Experiment you will grow and evaluate several lettuce cultivars, record data on growth, quality, nutrition and taste and then evaluate that data to make a recommendation as to which lettuce cultivar should be grown.

Some of the unique aspects of this “authentic experiment” are:

1. The experiment takes place over four to five weeks – the same as real plant experiments!
2. You will measure several plant characteristics. Rarely do scientists make their conclusions based on only one characteristic or parameter.
3. You will integrate multiple plant characteristics to determine and recommend a best cultivar.
4. You will answer the question “does your data support your hypothesis” the same way that scientist do.
5. There could be multiple best lettuce cultivars.
6. You will have the opportunity to use your data to make recommendations as to which lettuce should be grown in your garden and eaten.
7. You will have the opportunity to suggest what the next experiment should be.

We have tested this experiment with thousands of students. It engages them, connects them to science process, allows them to feel like scientists and do science that leads to recommendations that can be implemented. In short, it empowers students.

If you are interested, you have the option of recording data and doing the experiment “write up” on line using Google docs and Wikispaces. Your data will be put together will data from all of our experimenters to create an MSU Science Festival overall data set and recommendations.
When you sign up to do the Best Lettuce Experiment we will send you and email (subject line: MSU Science Festival Experiment) with the link to the online tools and to the compiled Science Festival community data.

If you have questions about the Best Lettuce Experiment contact Dr. Norm Lownds at: lownds@msu.edu

Experiment Notes:

Materials you will receive:

1. Four 2x2 containers
2. Seeds of four lettuce cultivars (Baby Star, Esmeralda, Pacheco and Simpson Elite)
3. Four white stakes to label each cultivar
4. Best Lettuce Experiment background sheet.

Planting your lettuce seeds:

1. Label each of the four containers – write the lettuce cultivar name on the white stake with a pencil or sharpie. Place one label in each container.
2. Sprinkle the seeds of each cultivar in the appropriate container (one cultivar in each container).
3. Scratch the soil surface and seeds just enough to cover the seeds with soil.
4. Tamp the soil surface lightly.

Growing your lettuce:

1. Place each lettuce container on a saucer (a plate, plastic container lid, aluminum foil) that will collect any water that goes through the container.
2. Place the four containers and saucers in a window sill where they will get plenty of light. If you have grow lights, you can put the containers under the grow lights.
3. Water each container. Be careful not to splash soil and seeds out of the containers. Water each container till a little bit of water comes out of the bottom.
4. Check your seeds/seedlings every day. Water whenever the media begins to dry out. If the media looks (and feels) wet, don't water for a day.
5. Keep a record of when the plants are watered.
6. Keep notes of any unique or unusual things that happen while growing the plants (ie. Didn't get watered for 3 days; got very hot on day 4; container was tipped over, etc.).

Collecting Data:

1. Plant growth: (measure weekly for 5 weeks)
   - Measure the height of each lettuce cultivar and record it on the data sheet.
2. Leaf Description: (describe weekly for weeks 2, 3, 4 and 5)
   - Describe the edge of the leaf and sketch the leaf of each cultivar
3. Leaf Quality: (rate weekly for 5 weeks)
   - Use the rating scale and data sheets to record the leaf quality for each cultivar.
4. Nutritional Value: (measure twice – week 3 and week 5)
   - Take a photo of each lettuce cultivar. Take the photo straight down on the lettuce and get close enough so the lettuce fills most of the photo frame.
   - Photos will be uploaded using the online Experiment tools.
5. Taste: (rate only once – week 5)
   - Use the taste rating scale and data sheets to rate the taste of each cultivar.

Grade Level / Experience / Interest Options

For older kids (middle, high school), the experiment can be done using method (2) to increase scientific rigor. You will have to decide which will work best for your kids.

Method	Advantages	Disadvantages
(1) Visible cultivar names	- Kids take great pride and ownership of the plants they have planted. - Makes this experiment more personal keeps a strong direct connection between the kids and their plants. - Almost no chance for getting things mixed up.	- It is hard for kids to be objective – they want their plants to be the best. - Not as rigorous from a scientific standpoint.
(2) Labeled only by letter or number	- “Blind” evaluation, same as scientists would do. - Promotes objective measurements and ratings. - Anticipation of finding out at the end which cultivar is best.	- Some kids not as engaged as when they don't know which plants they are measuring. - Tends to depersonalize the experiment, less direct connection to the kids. - Increased possibility of mixing cultivars up – be sure to handle and label everything carefully.

Measuring growth:

1. Specify the units of measurement that you will use and why. (We always take measurements in cm because scientific measurements are made using the metric system)
2. Discuss how to measure – from the soil up, from the bottom of the container, to the tallest leaf, etc. Alternatively, you can let your kids figure this out on their own. Hopefully someone will ask questions. Be sure to discuss how they measured at some point. Emphasize that different methods are all ok, BUT –
   • It is absolutely necessary that a group measures their plant the same way each time.
   • Later you are going to compare growth measurements with other investigators. To make that easier it would be best if everyone measured their plants the same way.
   • It is also very important that to write down a few notes about how you measured your lettuce so that if another group of scientists wants to replicate this experiment in the future they use the same procedures.

Rating Leaf Quality:

• Discuss making objective ratings. If you are using method (1) above: There is a huge tendency for kids to rate based on who planted the seeds. Almost always the lettuce they planted will get the highest ratings and lettuce that was planted by someone they don't like will get rated lower. Emphasize that they are rating based ONLY on what the leaves look like and that they are using the 1 to 5 scale. What the leaves look like does not depend on who planted the seeds.
• If you use method (2) above you can simply explain that because no one knows which cultivar is which, the measuring method insures that the measurements and ratings are as objective as possible.

Taste Test:

• Be sure to discuss objective ratings again.
• You could do multiple taste tests over time to see if taste changes as the lettuce gets older.

EXPLAIN DATA:

• Create tables and graphs of your data. Calculate averages. Compare your individual data to the entire Science Festival database.
• Use the data sheets to explain what your data means.
• OR - we have worked out the procedures for entering data into a Google docs spreadsheet, creating graphs and exporting the graphs to a Wiki for final experiment write up.
• Have each child make his/her recommendation as to which is the best lettuce.
• You could add a component here to write a recommendation to the principal, school board, lunch committee or a restaurant owner as to which lettuce would be the best for them to serve. Be sure to have kids use their data to support their recommendations. Please feel free to send this to Dr. Norm as well. We will read through the recommendations and respond.

ASK NEW QUESTIONS

• Use the experiment data sheets to record new questions that kids have based on this experiment.
• Have kids make suggestions as to the next lettuce experiment they would like to do.
• Send these experiment suggestions to the 4-H Children's Gardens and we will comment back. We will also consider using kids suggestions to create the experiments we do with kids in the future.

Download Data Sheets

• Click here to download the data sheets (.pdf file).