There Are Moles in Sweet Potatoes? (AIG IRP)
The concept of osmotic potential is difficult to grasp. Using this activity, students will be able to “see” how water moves based on differing concentrations of solutions. This activity will help students understand the process of osmosis and develop an understanding of sugar storage in different types of plants. The task also asks students the why of sugar storage and about the role of sugar (carbohydrates) in plants and animals. The task can be used while teaching homeostasis to solidify the concept of osmosis. This lesson was developed by NCDPI as part of the Academically and/or Intellectually Gifted Instructional Resources Project. This lesson plan has been vetted at the state level for standards alignment, AIG focus, and content accuracy.
Brief Description of Lesson/Task/Activity: The concept of osmotic potential is difficult to grasp. Using this activity, students will be able to “see” how water moves based on differing concentrations of solutions. This activity will help students understand the process of osmosis and develop an understanding of sugar storage in different types of plants. The task also asks students the why of sugar storage and about the role of sugar (carbohydrates) in plants and animals. The task can be used while teaching homeostasis to solidify the concept of osmosis.
Time Frame: 5-7 days
Type of Differentiation for AIGs:
Adaptations for AIGs:
Explanation of How Resource is Appropriate for AIGs: This activity requires AIG students to address relationships between concepts, move beyond the regular curriculum, focus on process and skills, develop their own hypothesis and to reach their own conclusions, and be active learners.
- Computer with internet
- Sweet potatoes
- Distilled water
- Stirring rod
Teacher Notes: Before assigning this activity, students need an intro to molarity and solution concentration. Students need to be able to understand that molarity is a measure of concentration (the number of moles of solute/liter of solvent), and that the higher the molarity, the more solute there is. Students need to know that moles are a measure of quantity. There are several videos/websites that explain molarity if you want the students to do independent study to learn about moles. Some websites are listed above. Students also need to know how to make a 1 M solution of sucrose and then create different dilutions of this to create a variety of different molarity solutions. Students will also need to be able to calculate percent mass lost or gained by the potato when placed in different molarity solutions.
Stage 1: Engage
Are sweet potatoes really sweet? Why do you say so?
Your company has been hired by the Sweet Potatoes ARE Sweet company to determine the amount of sugar in sweet potatoes. The company wants to start a new media campaign to convince children to eat sweet potatoes because they ARE sweet. As a researcher for your company, you are to determine the amount of sucrose in sweet potatoes and to then create an ad convincing kids to eat sweet potatoes because they ARE sweet.
Stage 2: Elaborate
(Consult Teacher Notes at the end of the task.)
Part 1) Develop and carry out an experiment to determine the amount of sucrose (in moles) in sweet potatoes. The experiment is to be based on the process of osmosis. Include a title, hypothesis, background info needed, procedure and a data table and graph of mass change vs molarity. Within the background info, include the type of sugar stored by sweet potatoes and why they store the sugar.
Once you have completed the experiment, research the actual amount of sucrose in sweet potatoes and then determine your percent error. If your percent error is greater than 5%, redesign the experiment and try it again.
Part 2) Develop a print ad, using your data, to convince kids to eat sweet potatoes since they ARE sweet. Include in your ad why sugar/carbohydrates are important and the type of sugar found in sweet potatoes.
Part 3) (IF THERE IS TIME) Your ad was such a success that the Beets are FUN to Eat Also company hires you to do the same thing for beets! Their company also owns a Sugary Sweet Syrup brand. The Beets are FUN to Eat company wants you to use their Sugary Sweet Syrup in your experiment.
Stage 3: Evaluate
Part 1) Develop a rubric to assess their experiment-the following is a suggestion
Part 2) Develop a rubric to assess their ad. The following is a suggestion. Ideally, the more detail you can add, the better.
Teacher Notes: If students need a little guidance as to how to develop the experiment, have them think of how water moves- from areas of high concentration to areas of low concentration. To help them visualize how this can be used to determine sugar content, have them mass a slice of sweet potato and then place it in pure water and mass again after 1 hour- use this data to lead a class discussion on how the water moved and what might happen if sucrose was added to the pure water. Use this discussion to lead students to discover that by adding different amounts of sucrose to water they can create a variety of different concentrations in which to place sweet potato slices. They will need to make several different solutions by adding different amounts of sucrose to water-the solution that causes the least amount of mass change will be the one that is closest to the percent of sugar in a sweet potato. 1 mole of sucrose has a mass of 342.29658g, therefore to make a 1.0 M solution add 342.3 g of sucrose to 1 L of deionized (DI) water and mix until the sucrose has dissolved. To make a .5 M solution, add 171.15 g of sucrose to 1 L of DI water. From this information students can then determine how to make other Molar concentrations.