Sugar Crystal Challenge

10월 02 2014

Source: IEEE

Summary Information

Keywords:

nanotechnology, molecules, crystals, sugar

Topic:

Physical Science

Chemistry

Estimated Time Required:

2-3 hours

Target Grade (Ages):

Grade 5 (Ages 10-11)

Grade 6 (Ages 11-12)

Grade 7 (Ages 12-13)

Grade 8 (Ages 13-14)

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LESSON

Goals and Prerequisites

Goals:

Through this lesson, students will:

Learn about nanostructures.
Learn about crystals.
Learn about surface area.
Learn about teamwork and working in groups.

Instructional Objective(s)

As a result of this activity, students should develop an understanding of:

nanostructures
surface area
problem solving
teamwork

Instructional Resources

Background:

Imagine being able to observe the motion of a red blood cell as it moves through your vein. What would it be like to observe the sodium and chlorine atoms as they get close enough to actually transfer electrons and form a salt crystal or observe the vibration of molecules as the temperature rises in a pan of water? Because of tools or 'scopes' that have been developed and improved over the last few decades we can observe situations like many of the examples at the start of this paragraph. This ability to observe, measure and even manipulate materials at the molecular or atomic scale is called nanotechnology or nanoscience. If we have a nano "something" we have one billionth of that something. Scientists and engineers apply the nano prefix to many "somethings" including meters (length), seconds (time), liters (volume) and grams (mass) to represent what is understandably a very small quantity. Most often nano is applied to the length scale and we measure and talk about nanometers (nm). Individual atoms are smaller than 1 nm in diameter, with it taking about 10 hydrogen atoms in a row to create a line 1 nm in length. Other atoms are larger than hydrogen but still have diameters less than a nanometer. A typical virus is about 100 nm in diameter and a bacterium is about 1000 nm head to tail. The tools or new "scopes" that have allowed us to observe the previously invisible world of the nanoscale are the Atomic Force Microscope and the Scanning Electron Microscope.

Materials:

Microscope or camera scope for classroom use
Dissolving Challenge: One set of materials for each team: Two clean thermal glass cups or measuring cups of at least 4 cup capacity (can be used in crystal challenge too), access to warm water, 1 teaspoon granulated sugar, 1 teaspoon powdered sugar
Crystal Challenge: One set of materials for each team: Two clean thermal glass cups or measuring cups of at least 4 cup capacity, 2 lengths of thin cotton string that is 1.5 times as long as the cup is tall, 2 Pencils or sticks, weight to hang on string (washer, screw), 3 cups of granulated sugar, 3 cups of powdered or confectioners' sugar, 2 cups very hot water (poured by adult)
Student Handouts

Procedure:

Dissolving Challenge:

a. Students pour one cup of warm water into each of two glass cups

b. Students add a teaspoon of powdered or confectioners' sugar in one cup and a teaspoon of granulated sugar in the other.

c. They observe which dissolves faster and answer questions regarding how surface area impacted the results

Crystal Challenge:

a. Teacher/adult first pours one cup of very hot water in to each of the two cups.

b. Students add 3 cups of each type of sugar into individual cups and stir to dissolve -- the water will appear perfectly clear when the sugar is dissolved. Note - alternate approach is to boil the water to dissolve the sugar -- if this approach is taken, an adult should prepare boiled sugar solutions.

c. Soak the string into the sugar water and tie one end to the pencil so that the other end hangs vertically in the sugar solution. A weight (washer, screw) can be added to ensure the string stays straight. You may also prepare the strings ahead of time, soaking them in the sugar solutions and letting them dry. With this method, there will be starter crystals on the string before being placed in the sugar solutions which can speed up the crystal process as the starter crystals provide a place for new crystals to form.

d. Observe the cups each day for four - seven days

e. Record observations during growth

f. Examine each of the resulting crystals under a microscope and record observations in table provided.

Evaluation - Students complete evaluation/reflection sheets

Extensions

Write an essay or a paragraph about how the surface area of different grades of sugar might be important to a baker who wanted to coat doughnuts with sugar. Would they need more granulated sugar than powdered sugar? Why, or why not?

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

These reflective questions will help assess student understanding:

What was one thing you liked about your design? What is its main weakness?
What is one thing you would change about your design based on your experience?
Are there algebraic and physical principles that can be applied to this activity?
How would you modify the instructions to create a better experience for the participants?

External Resources

TryEngineering
TryNano
National Nanotechnology Initiative
ITEA Standards for Technological Literacy: Content for the Study of Technology
NSTA National Science Education Standards
NCTM Principles and Standards for School Mathematics

Credits

This lesson was originally created for TryEngineering by IEEE.

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