Holiday Demonstrations and Activities
As the holidays arrive and students become focused on their winter vacation plans, performing demonstrations or doing fun class activities can help hold their wandering attention span while still teaching science concepts. The following are a few suggestions of activities or demonstrations that you and students may enjoy.
Conduct these activities in accordance with established laboratory safety practices, including appropriate personal protective equipment (PPE) such as gloves, chemical splash goggles, and lab coats or aprons. Ensure that students understand and adhere to these practices. Know and follow all federal, state, and local regulations as well as school district guidelines for the disposal of laboratory wastes. Students should not eat, drink, or chew gum in the lab and should wash their hands before and after entering or leaving the lab.
Topics covered: solutions, solubility, crystallization, crystal structure
A typical solution is one in which a solid is dissolved in a liquid. The amount of solid a liquid is capable of dissolving is limited. However, sometimes a solution can be manipulated so that it becomes supersaturated, that is, it contains a greater amount of dissolved solid than at its saturation point.
Increasing the temperature of the solution in this activity causes more borax to dissolve than at room temperature. As the temperature falls, the solution that was saturated at the higher temperature becomes a supersaturated solution. The excess solid does not remain in the solution indefinitely, and some of the dissolved chemical (borax) precipitates out to form new solid material (the crystals). This crystalline solid is deposited on a solid surface (the pipe cleaner), forming crystals.
Materials (per student)
- Borax, 65 g
- Beaker, 600 mL
- Stirring Rod
- Graduated Cylinder, 500 mL
- Craft Stick
- String, 30 cm
- Pipe Cleaner
- Paper Towel
- Balance (can be shared)
- Hot Plate (can be shared)
Create a shape using a pipe cleaner. This shape needs to fit into the beaker without touching the sides, and it should be only half as tall as your beaker. If you wish to make a basic snowflake shape:
- Cut the pipe cleaner into 3 equal lengths.
- Twist 2 of the pipe cleaner pieces together at their centers forming an “X” shape. This does not have to be done tightly, just enough to hold them together.
- Place the 3rd pipe cleaner piece on top of the X shape so that the center of the X and the center of the 3rd piece are aligned. Holding the center of the X and the center of the 3rd pipe cleaner piece together, wrap the ends of the3rd pipe cleaner piece around the center of the X. This should form a basic snowflake shape with 6 branches.
- Trim the ends to ensure that all of the snowflake branches are about the same length.
- Cut a piece of string about 30 cm in length.
- Tie 1 end of the string around your pipe cleaner shape. If you have made a snowflake shape, tie the string around the center, where all of the pipe cleaner’s pieces intersect.
- Tie the other end of the string to the middle of the craft stick.
- Place the pipe cleaner shape in the beaker and rest the craft stick on top of the beaker. Rotate the craft stick, winding the string around it, until the pipe cleaner shape is suspended.
- Remove the craft stick and shape from the beaker, making sure not to unwind the string.
- Place 475 mL of water into the beaker.
- Heat the water on the hot plate until it is boiling. Using heat protection, remove the beaker from the heat.
- Add 65 g of borax to the water, and stir until the borax is mostly dissolved.
- Place the pipe cleaner shape into the borax solution, again resting the craft stick on top of the beaker. Ensure that the pipe cleaner shape is completely submerged and not touching the sides or bottom of the beaker. If it is, adjust the string by manipulating the craft stick.
- Allow the pipe cleaner shape to remain undisturbed for at least 24 hours.
- Remove the pipe cleaner shape from the solution and place it on a paper towel to dry.
Topics covered: oxidation-reduction reactions, reversible reactions, indicators, rates of reactions
In this activity a redox indicator (indigo carmine) changes color as a result of electron transfer. The introduction of oxygen through swirling causes the indigo carmine to turn green as it is oxidized. Upon standing, the indigo carmine is reduced by the glucose, causing the indicator to turn yellow. A semiquinone intermediate causes a red color between the yellow and green. You can influence the rate in which the color changes. Higher temperatures and greater concentrations cause the color change to occur more rapidly.
Materials (per demonstration)
- Glucose, 7.5 g
- Sodium Hydroxide, 3.75 g
- Water, Distilled or Deionized, 500 mL
- Graduated Cylinder, 100 mL
- Indigo Carmine
- 2 Stirring Rods
- 2 Beakers 600 mL
- Erlenmeyer Flask or Bottle, 1,000 mL
- In a 600-mL beaker add 7.5 g of glucose to 375 mL of water. Stir the mixture until the glucose is dissolved.
- Add a very small amount of indigo carmine to the glucose and water mixture. The solution will turn dark blue.
- In another 600-mL beaker add 3.75 g of sodium hydroxide to 125 mL of water. Stir the mixture until the sodium hydroxide is dissolved.
- Pour the sodium hydroxide solution into the 1,000-mL Erlenmeyer flask.
- Add the glucose solution to the flask. Swirl them to mix. The solution should turn green.
- Allow the solution to rest. It should turn a yellow or red color. If the solution is yellow and you would like to have it change from red to green, swirl it very gently until it starts to change color.
- Once the solution is red, swirl it vigorously to get it to change to green. Upon resting, the solution will again turn yellow or red.
Marbled Gift Wrap
Topics covered: properties of water, polarity, properties of soap
Foam shaving cream is primarily composed of air and soap. Soap is an amphipathic substance, which means that its molecules have both a hydrophilic (water loving) and a hydrophobic (water fearing) end. Because of this, soap is able to combine with water and also with many oils. Because of the shaving cream’s hydrophobic end, when you drop food coloring (a hydrophilic substance) onto shaving cream, the coloring does not spread.
Paper is primarily composed of cellulose (a hydrophilic substance). When you place paper on top of the shaving cream and the colored pattern, the food coloring is attracted to the paper, causing the colored pattern to transfer permanently to the paper.
Materials (per student)
- Foam Shaving Cream
- Liquid Food Coloring
- Waxed Paper
- Paper or Card Stock
- Spread out the waxed paper so it covers an area slightly larger than the paper you are going to marble.
- Squirt shaving cream on the waxed paper and smooth it out with a ruler so that you have at least 2 cm of shaving cream covering the paper.
- Place drops of the food coloring that you like on the shaving cream.
- Using toothpicks, swirl the colors around in the shaving cream to create a pattern that is pleasing to you.
- Place the paper on top of the shaving cream so that it is lying flat. Pat it very lightly to ensure that the entire surface of the paper contacts the shaving cream.
- Grab the paper by 1 corner and peel the paper up from the shaving cream.
- Lay the paper flat on a dry surface with the shaving cream side up.
- Allow the shaving cream to dry.
- Using the ruler, scrape any remaining shaving cream from the paper.
Topics covered: oxidation-reduction reactions, activity series
In this activity students perform a redox reaction in which silver crystals take the place of copper in copper wire. The copper changes from its elemental form to its aqueous ionic form. During the course of the reaction, the silver ions are reduced and are removed from the solution. The silver ions are deposited on the copper wire as elemental silver. The copper metal is oxidized and forms ions in the solution, changing the solution from colorless to light blue. The following reaction occurs:
Materials (per student)
- 0.1 M Silver Nitrate, 50 mL
- Copper Wire
- Beaker, 50 mL
- String, 20 cm
- Craft Stick
- Shape a piece of copper wire into an object of your choosing, such as a star, snowflake, Christmas tree, or other shape. This shape must be small enough to hang suspended in the beaker without touching the sides or bottom.
- Tie 1 end of the string to the wire shape.
- Tie the other end of the string to the craft stick.
- Place the wire shape in the beaker and rest the craft stick on top of the beaker. Rotate the craft stick, winding the string around it, until the wire shape is suspended.
- Pour silver nitrate into the beaker until the shape is covered.
- Allow the shape and solution to remain undisturbed. Examine it after half an hour has passed. If you leave the shape in the silver overnight, the shape may disintegrate.
Other Activities and Demonstrations
- Snow polymer: Hydrate sodium polyacrylate, snow polymer, to form dry fluffy "snow." Challenge your students to design an experiment using this wintery chemical. Teach students about super absorbent polymers, physical properties, and the scientific method.
- Silver bottle: Teach students more about redox reactions as you conduct a demonstration in which silver is deposited on the inside of a glass bottle. You can then have students use the same procedure with additional chemicals to silver the inside of their own glass ornaments.
- Holiday flame test: Explore different elements and their emission spectra with a flame test. For holiday flare, pick elements that match your holiday colors, or pick elements that match your school colors. Teach or enforce your students' knowledge of atomic theory and the Bohr atomic model.