Target Grade Level / Age Range:
3, 30 minute time periods
- Day 1:
- Tasting Items
- Plan Investigation
- Day 2:
- Run Investigation
- Day 3:
- Present Investigation Findings
- Write Letter
In this lesson students solve a problem as they investigate how grapes are processed and their physical properties.
- Frozen Grapes (you can make these by placing table grapes in the freezer for 24 hours)
- Observation Log (1 for each student)
- Investigative Log (1 for each group)
- Testing Station Descriptions
Essential Files (maps, charts, pictures, or documents)
- Vineyard: a plantation of grapevines producing grapes
- Raisins: a dried grape
- Jam: a thick, sweet spread with crushed pieces of fruit that is made from fruit and sugar
- Jelly: a sweet, clear, semisolid spread made from fruit juice and sugar boiled to a thick consistency.
- Preserves: a thick, sweet spread made with chucks of fruit and sugar
- Physical Property: a property of an item that is measurable
- Physical Change: a change in physical property such as color, odor, etc.
- Investigation: a process of discovering and evaluating facts to determine the truth
Background – Agricultural Connections
- Vineyards and what they are
- Vineyards are areas where grapes are grown. There have been many obstacles throughout history in grape production, such as blizzards, soil types, climate, pesticides, and/or governmental actions. Currently Iowa has 1,300 acres of vineyards, compared to only 30 acres 20 years ago.
- Watch this video about how Welch’s grapes are cared for.
- How are raisins made
- There are a few different ways to make raisins.
- The traditional way is to remove the grapes from the vine, either by hand or machine. The grapes are then laid out in the sun on paper to dry. Once they are rolled up and dried, the grapes are transported to a packaging center where they are cleaned and packaged for distribution.
- An alternative method is called “dry on the vine.” The branches on the grape plant are trained to grow up a wire. This allows the grapes to hang below the wires that support the plant. Once the grapes are ripe and the sugar content is at the right level, the vines are cut. The grapes then dry on the wire supports and are harvested once dry.
- Another method is to use a dehydrator. A dehydrator is a machine that removes water from the grapes through the air. This process is much shorter than the other methods.
- Learn more about how grapes are dried into raisins in this video
- Watch this video to review the traditional and dehydrator methods of making raisins.
- After reading about different methods for grapes being turned into raisins, can raisins be turned back into grapes?
- Raisins would need to be rehydrated through a process to reach their original state. Students will investigate this process during their experiment.
- There are a few different ways to make raisins.
- Juice being made
- Grapes are brought into a facility where they are going to be transformed into juice. The first step in juice making is removing the stems from the grape. After that is complete, the grapes are ready to be crushed. Following the crushing, the juice is sent to a mixer where cellulose is added. Cellulose is a thickening agent, which allows more juice to come out from the solids. Shortly after the mixture is complete, the juice is sent to a drag screen. Brushes are used during this process to separate the juice from the solids. To ensure all juice has been squeezed out of the grapes, the remaining solids are sent to another step called a vertical screw press. This technique gets all remaining color, flavor, and juice out of the solids. The cellulose that was added prior is removed in this step. Soon after the pressing stage is finished, the juice is sent to be concentrated. Concentrating is when the water is removed from the grape juice creating a concentrate. Finally, the juice is sent to be bottled, which completes the grape juice making process. Watch how Welch’s Grape juice is made.
- Jam/jelly being made
- What’s the difference between jelly, jam, and preserves? Jelly is made from fruit juice, while jam is made from the crushed fruit. Preserves are thicker and contain fruit pieces.
- Jam is made fruit, pectin, acid, and sugar. Each of these ingredients plays a key role in the process. The fruit is the star of the show, it provides the flavor to the jam. Pectin is a thickening agent which helps the fruit transform into the gel form. Acid, which is present in citrus fruits, is the preserving agent in jam. Last but certainly not least is sugar. Sugar assists the jam in becoming a thicker form and gives the sweet taste we all look for.
- Jam and jelly are made in very similar ways, but the main difference is in the fruit that is used as explained above. The fruit or juice is made into a thicker consistency by adding pectin and sugar. This mixture is heated, which also aids in the thickening process. The acid is then added to help preserve the jam/jelly.
- Watch how Grape Jelly is made.
Interest Approach – Engagement
- What crops are grown in Iowa?
- Corn, soybeans, wheat, grapes
- Set up a tasting station for each of the following: frozen grapes, raisins, juice, and jam/jelly. Set testing station descriptions with each item.
- Have students wash hands thoroughly before tasting the items. Discuss with the students why this is important
- Germs can cause you to get sick, etc.
- Hand out the data sheet for students to fill out. Students will then travel from station to station exploring different preserved grapes while filing in their data sheet.
- Optional Modification: instead of having stations, hand out to items one at a time for tasting.
- Have students share their findings with an elbow partner.
- Divide students into 4 different groups, one for each item, to design their investigation.
- Prompt the students with the following question while handing out the investigative sheet. Can any of these preserved items be returned to the original grape state? Students will work to answer the scientific question. They will create a hypothesis and the procedure to follow while conducting their experiment.
- While students are completing their investigation planning, walk around and prompt questions.
- Examples: How did the grapes become (jam/jelly/juice, etc.)?
- Why do you think heating/freezing/adding water will return grapes back to their original form?
- After each group is finished with their investigative sheet, allow time for the groups to run their investigation.
- Walk around the classroom during this time to make sure all experiments are running smoothly.
- If a group finishes early, have them predict what the other items need to return to their original form.
- Once the investigation is complete, have the groups select a presenter.
- Have each group present their investigation to the class, explaining why they chose the steps they did.
- Raisins: We chose to soak our raisins in water and warm them. We decided to do this because the raisins are dried, which means they need water to return to grapes. We also chose to heat them because freezing the mixture would turn the water to ice.
- Frozen Grapes: We chose to heat our frozen grapes because they have been frozen.
- After each group has presented, ask the students the following questions
- What were your initial predictions? Were they correct?
- What did you discover?
- Which items can and cannot be returned to their original state?
- Which item was your favorite?
- Share the following scenario with your students. An Iowa vineyard is looking for more ways to preserve the grapes they produce. After tasting the items and exploring, what preserved grape would you recommend to the vineyard?
- Have students write a letter to the vineyard with their recommendation.
- Have students share out which item they recommended and why.
- Have students share their letter with family or a friend.
- Optional Modification: Contact a vineyard to see if your class can send them their letters.
Did you know? (Ag facts)
- California is the #1 grape producing state
- Different types of grapes are grown in different climates
- Grapes are classified as berries
- Find what grapes are grown near you
Suggested Companion Resources
- Iowa Agriculture Literacy Foundation
Agriculture Literacy Outcomes
- T2.K-2.d. Identify food safety practices to demonstrate at home
- T5.k-2.d. Identify plants and animals grown or raised locally that are used for food, clothing, shelter, and landscapes
Iowa Core Standards
- 2-PS1-1. Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties.
- 2-PS1-4. Construct an argument with evidence that some changes caused by heating or cooling can be reversed and some cannot.
- Tell a story or recount an experience with appropriate facts and relevant, descriptive details, speaking audibly in coherent sentences. (SL.2.4) (DOK 1,2)
- SS.2.4. Construct responses to compelling questions using reasoning, examples, and relevant details.
Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes. (2.MD.A.1) (DOK 1)
Measure to determine how much longer one object is than another, expressing the length difference in terms of a standard length unit. (2.MD.A.4) (DOK 1,2)