Explore the world of nanometers by arranging eight objects from largest to smallest.
Time needed: 15 minutes
A nanometer is used to measure things that are very small. Atoms and molecules—the smallest pieces of everything around us—are measured in nanometers. The prefix “nano” means 10-9, so a billion times less than a meter. For example, a water molecule is less than 1 nanometer. A typical germ is about 1,000 nanometers.
The wavelength is the distance over which a wave’s shape repeats. Examples of waves include sound waves, light, and water waves.
Light is electromagnetic radiation and it moves in a wave pattern that has different lengths. Different types of light have different wavelengths. The exact wavelength determines the color we see. Other animals can see wavelengths that we cannot. Infrared, radio waves, X-rays, and gamma rays are all wavelengths outside the visible spectrum of colors we can see.
For this activity, you’ll research eight objects of the extremely small nanoworld and order them largest to smallest.
It’s very important to protect yourself and your identity when using the internet. Make sure to sign the Girl Scout Internet Safety Pledge.” Always follow home internet rules and only visit websites you have permission to visit.
First, look at a centimeter and millimeter on the ruler. Compare that to the list of small metric measurements below with a scale from a centimeter to a picometer. All the measurements you will be researching are measured in nanometers.
On your computer, smartphone, or tablet, research the size of a gold atom, DNA helix, nanowire, hair, red blood cell, bacterium, and dust particle.
Write the size in nanometers on your paper. When you have all eight sizes, order the items from largest to smallest.
Check your answers against the Correct Sequence handout.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Explore the World of the Small: Measuring in Nanometers | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Use physical science and engineering to design, draw, and build a vehicle to meet specific challenges.
Time needed: 60 minutes
Gravity is a force between Earth and an object that pulls everything toward Earth. Friction is another type of force. It is the force of one object rubbing against another. When something like a vehicle rolls down a ramp, gravity is the force pulling it down and friction is the force that stops it from rolling.
In this activity, you’ll discover the different forces at play as you run tests on a ramp and make engineering design revisions.
First, use cardboard and a stack of books to construct a ramp.
Try to find a smooth, ideally uncarpeted space on which the vehicles can travel after descending the ramp. This activity also works on a carpeted surface if the carpet is relatively smooth.
Next, measure and mark 3 feet and 6 feet beyond the end of the ramp for the vehicle design tests.
Once you have a ramp, choose your design challenge. Do you want to:
Then sketch a vehicle design on paper to meet the challenge. This should be a two-dimensional design with front and side views.
Next, build the vehicle using materials you find around the house. Decide what will work best to roll down the ramp and carry a load.
Then test the vehicle by releasing it and letting it roll down the ramp, observing what happens.
Lastly, measure and record the distance the vehicle traveled from the bottom of the ramp to the location where it stopped.
Consider what worked and what didn’t. What could you change to make your vehicle meet the design challenge?
If you had fun, you can select another challenge and redesign the vehicle to meet the goal of the new challenge.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Which Force Is With You? A Motion and Design Lesson | Smithsonian Science Education Center © 2019 Smithsonian Institution.
Use size and distance relationships to make an Earth-to-moon distance model.
Time needed: 5–15 minutes
Scientists and engineers use and construct models as helpful tools for representing ideas and explanations. Models are helpful tools when representing something that is very large, such as a planet, or a very large distance, such as those between planets in outer space.
Use construction paper and string to model Earth, the moon, and their distance from each other.
First, create a model of Earth.
Cut the sheet of blue construction paper into 1-inch strips on the long side of the paper.
Tape the narrow end of two strips together.
Use your measuring tape or ruler to measure 18 inches on the paper strip. Use your pencil or pen to draw a mark at the 18-inch point on the paper. If your strip of paper is less than 18 inches long, tape another strip to the end and measure again.
Cut the paper strip where you marked, so your strip of paper is 18 inches long.
Create a ring with your paper strip and tape the two ends together to make your model Earth.
Then create a model of the moon.
Cut the sheet of white construction paper into 1-inch strips on the long side of the paper.
The moon is about one-fourth the size of Earth. Your Earth model is 18 inches in diameter, so one-fourth of that is 4½ inches. Use your measuring tape or ruler to measure 4½ inches on the white paper strip. Put a pencil or pen mark at 4½ inches on the paper strip.
Cut the paper strip where you marked so your strip of paper is 4½ inches long.
Create a ring with your paper strip and tape the two ends together to make your model moon.
Lastly, model the distance from Earth to the moon.
The moon is a little less than 10 Earth circumferences (the blue ring) from Earth.
Wrap your string around the blue paper ring (your model Earth) 10 times.
Cut the string after you have wrapped it around your Earth model 10 times. That’s a model of the distance from Earth to the moon!
Tape one end of the string to your Earth model and the other to your moon model.
You now have a scale model of Earth, the moon, and the distance between them!
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Mission to the Moon Model | Smithsonian Science Education Center © 2019 Smithsonian Institution.
Calculate how much water is used in an imaginary neighborhood to better understand and meet the challenges of water accessibility.
Time needed: 60 minutes
Many international organizations use access to safe drinking water and hygienic sanitation facilities as a measure for progress in the fight against poverty, disease, and death. According to the World Health Organization and UNICEF, in 2015, 663 million people lacked access to an improved source of water, such as a piped household water connection, public standpipe, borehole, protected dug well, protected spring, or rainwater collection.
Improved sources of water most often come from groundwater. Groundwater is water held underground in the soil or in pores and crevices in rock. Engineers make wells to pump groundwater to homes.
In this water conservation activity, you’ll explore water usage and calculate the water usage of a household in Sunnybrook Circle, an imaginary neighborhood. Then you’ll design and build a “pumping station” to meet the challenge of moving the water the household needs from the reservoir bucket to their house bucket.
Part 1: Compare estimates to actual water usage figures from the U.S. Department of the Interior.
Get started by thinking about your own water usage. How many gallons of water do you think you use in a day?
Create three columns on a sheet of notebook paper by drawing two vertical lines. Label the three columns “Usage,” “Estimate,” and “Department of Interior.”
On the lines in the first column (under the “Usage” header), add this list of activities, with each activity on its own line: brushing teeth, washing hands, shower, bath, toilet flush, dishwasher, dishes by hand, clothes washer, drinking, outdoor watering, and pet.
Write your estimate for how many gallons of water each activity would use in the middle column.
Add these usage figures from the Department of the Interior to your third column:
Compare your estimates (in the middle column) to the actual usage figures from the Department of the Interior (in the right column). How close were your estimates?
Part 2: Calculate water usage for a Sunnybrook Circle household.
Next you’re going to calculate the usage for a household in an imaginary neighborhood called Sunnybrook Circle.
To get started, choose a household from the Sunnybrook Circle household descriptions below.
Once you’ve chosen a household, draw the house on a sheet of blank paper as you imagine it on Springbrook Circle, with the house number included.
On a second sheet of blank paper, draw the face of each family member and their pets, along with any other sources of water usage mentioned in the household description. Leave space for recording the estimated number of gallons of water that each person, pet, or other source of water usage requires in one day.
Then use the Department of the Interior’s water usage figures from Part 1 to estimate the water usage for each family member. Record that number under each face, pet, or other source of usage on your paper.
To find the total water usage for the household, add up the total number of gallons of water needed for the household. Write this number on the bottom of the paper.
Part 3: Pump water for your Sunnybrook Circle family.
Next, design a pump station to move the amount of water that is needed for your household from one bucket to another bucket (1 mL = 1 gallon).
The constraints (limits) for this activity are:
Create your pump station by attaching the syringe to the three-way valve and using the connectors to connect the airline tubing. The pump station must reach between the bucket you are pumping water from and the one you are pumping water into. As you create your design, remember there is no one “right way” to create the pump station. Part of engineering is testing out many different ideas to find the one that works best. Test how the three-way valve holds water in the tube once the syringe has pulled water into the tube. Try moving the syringe and three-way valve closer and further from the bucket from which you are pumping water. Does it work better one way or the other?
Once you have the pump station working, you must pump in milliliters the number of gallons their household needs from the reservoir bucket to the household bucket.
Optional: Once you have completed moving the amount of water that is needed for your household, try the activity with another Sunnybrook household.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Where Does the Water Go? Calculating a Neighborhood Water Footprint | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Use everyday materials to design and execute code for specific robot movements.
Time needed: 60 minutes
Humans have used visual and auditory codes for thousands of years to communicate information. Things like barcodes, racing flags, smoke signals, whistle codes, and tap codes convey messages. Scientists and engineers use codes to program things like computers and robots.
With a partner, design code to convey movements for a model robot. Your partner will execute the code and perform the robot’s movements.
Part 1: Practice sending and receiving tap codes using a Polybius square.
The Polybius square was named after an ancient Greek cryptographer. It has five horizontal rows and five vertical columns representing the letters of the alphabet with the letters C and K sharing a square.
Each partner should create six columns on a sheet of paper. With the long edge of the paper facing you, fold the paper in half vertically, from left to right. Then fold the paper into thirds vertically. Unfold the paper and you should have 6 vertical columns. It doesn’t matter if they aren’t exactly the same width. What's important is that there are six columns.
Then create six rows. Flip your paper so that the short side faces you and repeat the folding process you used to create the columns. Fold the paper in half vertically and then fold the paper in thirds vertically. Unfold the paper, and you now have six rows and six columns.
Use a ruler to draw lines where the creases are. This is optional, but it makes it a little easier to see the squares.
Fill in your Polybius square. With the long edge of the paper facing you, label the top row by writing 0 through 5, in order, in the squares. Using the 0 in the first square, label the first column 0 to 5. This row and column make up the tap code.
In a different-color marker or pencil, fill in the letters that correspond to the code by filling in the row next to the number 1 with the letters A through E from left to right. Add a K in the square with the letter C. These two letters share a square.
Complete your Polybius square by filling in the remainder of the alphabet. The row starting with 2 will be for F through J. The row starting with 3 will be L through P. The row starting with 4 will be Q through U. And the row starting with 5 will be V through Z.
You have now designed your code! Make sure that each partner’s Polybius square is the same as yours or you won’t be able to decipher the code.
Next, use the code to send messages. Decide which partner is sending the code and which is receiving. Find a hard surface, like a table or floor, that allows you to hear if you tap lightly with your finger or pencil.
The code sender taps two sets of numbers. The first set of taps tells which of the five rows the letter is in. The second set of taps tells which of the five columns the letter is in. For example: M would be three taps followed by a pause and two taps because it is in the third row and second column. The pause between letters should be longer than the pause used between the row and column taps for a letter.
The partner receiving the code listens carefully to the timing of the taps to figure out the letter. For clarity, an X is tapped at the end of a sentence and a K is tapped by the receiver to acknowledge that the message has been received.
Once you’ve sent a message, use your tap code to send messages back and forth!
Part 2: Code robot motions.
Now that you’ve sent and received tap codes with the Polybius square, design and execute your own code to send movements to your partner, who will be your model robot.
Create another Polybius square by folding a new sheet of paper following the instructions from Part 1. Label the first row and column with 0 through 5, like you did before. This should be done by both partners.
Then fill in the movements that correspond to the code. Instead of the alphabet, the tap code should correspond to movements. For example, you might include “forward one step,” “backward one step,” “turn around,” “jump,” “right arm up,” “right arm down,” “left foot up,” “left foot down,” “head turn right,” “head to center,” “sit,” or “stand.”
Write one movement in each square. Remember, it is important that both partners have the same Polybius square or you will not be able to execute the code properly.
After you’ve created your Polybius squares, execute the code to send messages. Just like before, the code sender taps two sets of numbers, and the code receiver does the motion that corresponds with the code.
Once you’ve executed the code, switch roles so you both have a chance to be the code sender and the model robot!
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, What's the Code? Coding Robot Movements Using Sound | Smithsonian Science Education Center© 2019 Smithsonian Institution.
Find out about mosquitoes as you explore their anatomy, environments, what attracts them, why mosquitoes “bite,” and the dangerous diseases they carry.
Time needed: 30 minutes
Mosquitoes are insects that live all over the world, most commonly in warm, wet climates. Worldwide, there are over 3,500 different species. Scientists study mosquitoes because they carry disease. Some types of mosquitoes transmit diseases that affect humans, including malaria, chikungunya virus, dengue fever, Zika virus, and West Nile virus. By transmitting diseases, mosquitoes are the deadliest animal on Earth.
For the activity, play a game against a friend or sibling to learn more about mosquitoes.
Part 1: Research mosquitoes.
Get ready by researching mosquitoes with the other player. Work together to find answers to these questions:
It’s very important to protect yourself and your identity when using the internet. Make sure to sign the Girl Scout Internet Safety Pledge. Always follow home internet rules and only visit websites you have permission to visit.
Part 2: Play the game.
Choose which person will be Player 1 and which will be Player 2.
Go over the goal, rules, and other information for the game:
To start playing, have Player 2 choose a category for their question from the Be Mosquito-Smart Questions handout. It may be helpful to print the questions so that you can mark them off once they have been asked.
Player 1 can then read a question from that category for Player 2, and if needed, repeat the question before starting the timer.
Player 2 then has 20 seconds to answer.
If Player 2 answers the question correctly, they draw the mosquito body part on their paper. If Player 2 answers the question incorrectly, they do not draw anything.
After Player 2 draws the body part (or does nothing), switch roles so that Player 1 chooses a category and Player 2 reads the question to Player 1.
Continue alternating who reads questions until one player wins with a fully drawn mosquito!
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Be Mosquito Smart: Know the Enemy | Smithsonian Science Education Center (si.edu)© 2019 Smithsonian Institution.
Create a multicell battery using household materials.
Time needed: 60 minutes
Tip: Materials such as the multimeter, copper wires, and LEDs can be purchased at a hardware store or online.
Chemists and battery designers are constantly challenged to produce safe, longer-lasting, and environmentally friendly batteries to meet society’s energy needs. A multicell battery is a battery consisting of a group of cells that are single-unit devices converting chemical energy into electric energy. The chemical reactions in a battery involve the flow of electrons from one electrode to another.
In each cell, a battery uses a positively charged electrode by which the electrons leave, called an anode, and negatively charged electrode by which electrons enter, called a cathode. The anode and cathode interact in a substance that produces an electrically conducting solution called an electrolyte. The flow of electrons provides an electric current that can be used to do work.
For this activity, your task is to assemble a battery capable of providing usable electricity using only household items. You’ll test your design using a multimeter, a device that measures the electrical properties of voltage, current, and resistance. You will also demonstrate how the energy produced from your design illuminates one or more light sources.
Your battery will use a galvanized (zinc-coated) nail as the anode, a copper wire as the cathode, and vinegar and water as electrolytes. The parts, or components, are assembled in each compartment of an ice cube tray, representing individual cells of a multicell battery.
Safety: Used vinegar can irritate the skin. In case of contact, wash your hands with soap and water.
Criteria are the goals a design must meet. The criteria for this activity are:
Constraints are the limits on a design. This activity has one constraint: your battery must use only the materials listed.
How to Build a Battery:
Step 1: Wrap a copper wire (cathode) around the midsection of a zinc-coated nail (anode), leaving a 1- to 2-inch overhang. Place the nail into the first compartment (cell) of the tray and the loose end of the copper wire into the compartment across from the first.
Step 2: Repeat Step 1 so that eight compartments are connected in series (positive to negative), resembling a U shape. Be sure that no copper wire’s loose end is in direct contact with a nail in the same cell, as this will short the cell.
Step 3: Fill each of the eight compartments nearly full of vinegar. Ensure each nail and connected wire is submerged.
Step 4: Use your multimeter to compare the voltage produced by individual cells with that produced by all cells together. To do this, submerge the red probe of the multimeter in the first cell and the black probe in each other cell through to the last. Your cells should look like the photo in the Step 4 handout. Record the total voltage on a piece of paper.
Step 5: Connect the first and last cubes by placing an LED between them (one leg of the LED submerged in each cell) to demonstrate the produced power. Change which leg is in each cell if the LED does not illuminate.
Step 6: Remove all of the prepared nails, rinse them, and place them in the eight unused compartments on the opposite end of the ice tray. The arrangement should resemble steps 1 and 2.
Step 7: Fill each of these new compartments nearly full of tap water.
Step 8: Test the produced voltage as in Step 4 and record the result. Connect the first and last compartments by placing an LED between them to demonstrate your battery’s power.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Engineering Batteries | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Use circuits to build a multicolored night light.
Time needed: 60–90 minutes
Tip: Materials like copper tape and LEDs can be purchased at a hardware store or online.
Circuits allow us to use electricity in helpful ways. We find them everywhere, and they are an important part of our daily lives. Circuits are in our toys, computers, televisions, telephones, and even the lights in our homes. All circuits have an energy source such as a battery, an energy consumer such as a light bulb, and a way to connect the two, such as a wire or material capable of transporting electricity, called a conductor.
Circuits can be open or closed. A closed circuit is one that has an unbroken path for electricity to follow. An open circuit is one that has a gap or break in the path. Because of this gap, electricity cannot flow in an open circuit and the device remains unpowered or off. A device called a switch can be used to open or close circuits.
In this activity, you’ll explore the different kinds of circuits and design a multicolored night light.
To get started, review the criteria and constraints for the activity.
Criteria are the goals a design must meet. The criteria for this activity are:
Part 1: Test material conductivity.
Some materials conduct electricity, and some do not. We call these materials conductors and insulators, respectively. Can you predict which materials are conductors?
First, peel the paper back from the copper tape and stick the copper tape along the orange path (as shown in Setup handout). Connect one piece of the tape to the battery’s positive (+) side (called a terminal) and the other to the battery’s negative (-) terminal. Place clear tape over the battery to better secure it to the paper.
Next, unfold two paper clips and cut the remaining test materials (wood craft stick, paper strip, aluminum foil, copper tape) into two sections and tape them down along the top and bottom sides of the path using copper tape. Leave a small (1 cm) gap in the center.
Hold a colored light across each of the test materials (long leg pointing upward) to test which materials can conduct electricity. Try flipping the light over if it does not light up.
Part 2: Build your multicolored night light.
Now that you understand the basics of how circuits work, use what you’ve learned to make something useful and fun—a multicolored night light!
Build your multicolored night light circuit using the design in Night Light handout and what you’ve learned. Include switches to control which color light turns on and off.
Use a Styrofoam cup as a lamp shade by placing it over the lights.
Lastly, experiment with the different switches to produce any color light you choose. For example: blue + red = purple; green + red = orange; red + green + blue = white.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Engineering Circuits | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Construct a pendulum that swings 60 times a minute, marking one second with each swing.
Time needed: 5–15 minutes
Pendulums are at work every day in construction, recreation, music, ceremony, science, and art. Every pendulum is some kind of mass hung on a nearly weightless string or rod from a fixed point that swings freely by the force of gravity and remains in motion until another force stops it.
First, cut a piece of string 50 cm (20 inches) long.
Tie a paper clip to the end of the piece of string. Tie the other end of the string to a hanger. The string should be able to swing back and forth from a fixed point on the hanger.
Time and record the number of swings in a minute. One swing equals the complete swing movement: forward and back.
Experiment by putting various weights of washers on the paper clip and swinging them on the 50-cm (20-inch) string pendulum.
Ask yourself, “Did the weight of the bob (washer) change the number of swings in a minute? If the weight doesn’t affect the number of swings, what else might?”
Try changing the length of string. Ask yourself, “Do you think you need a longer string or a shorter string to have the pendulum swing 60 times in a minute?”
Keep trying different lengths of string to meet the 60 swings per minute challenge.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Swing Along with a Pendulum: Clocking a Second | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Use everyday materials to construct and package an adhesive bandage for an emergency.
Time needed: 60 minutes
When people get injured, they sometimes need a bandage to stop bleeding. A bandage must be absorbent to stop the bleeding and adhesive to stick to the skin but not the cut. It must also be sterile and flexible so that the person wearing it can move without the bandage falling off, and waterproof to keep air and water out of the wound. Lastly, it should be easy to use during an emergency.
Test and use everyday materials to create a bandage that can be used in different scenarios.
To get started, choose an “I Need a Bandage” scenario from the list below.
“I Need a Bandage” scenarios:
Each “I Need a Bandage” scenario indicates how badly the injury is bleeding. Measure and draw (with the red washable marker) the wound on yourself as described in the scenario.
Your bandage will need to cover the size and shape of the mark you have just drawn on yourself. It will also need to absorb the amount of liquid (blood) in the scenario.
You can use any of the materials you have to create your bandage, so it may be helpful to test the materials first to discover their properties. Are they absorbent, adhesive, sterile, flexible, waterproof, and easy to use?
Create a spreadsheet on a piece of paper that lists all the materials and all the properties to document the properties of each material.
Then test the absorbency of each material and whether they’re waterproof by using the eyedropper to put water droplets on the materials. Use your hands to test if the materials are flexible or adhesive. Write down what you learn on your spreadsheet and any other notes that might help with your design.
Next, design your bandage. Think about why you chose a particular material. Which materials are adhesive? Which materials are absorbent? Which materials are flexible?
Once you’ve designed a bandage to meet the needs of the injury in your scenario, design a package or wrapper for the bandage, again using any materials you have. Use your creativity to give your product a brand name, logo, or design for the wrapper. You might also need to create instructions for opening the wrapper.
After you’ve created your bandage and packaged it, test your bandage on the cut you drew on yourself. Does it work?
Optional: Pick another “I Need a Bandage” scenario and design another bandage! Then compare your two bandages. Did you use different materials for each design? Why?
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Ouch! I Need a Band-Aid®: Designing, Constructing, and Packaging a Band-Aid | Smithsonian Science Education Center. © 2019 Smithsonian Institution.
Create a balanced sculpture of two to five rocks kept in place by nothing more than shape, weight, and friction.
Time needed: 60 minutes
A rock sculpture is also known as a cairn. A cairn is a human-made stack of stones. These rock sculptures have been used around the world for thousands of years. Some historical uses for rock sculptures have been for monuments, burial sites, navigational aids, or religious ceremonies. Cairns in the present day are most often used as trail markers to guide hikers.
In this activity, test your skills and learn about balance as you design a simple sculpture using a rock as a fulcrum to balance two or more river rocks.
For this activity, create a unique, temporary balanced sculpture from two to five river rocks of various shapes and sizes.
First, choose several river rocks for your rock sculpture. Start with three river rocks and a ruler or paint-stirring stick. Make a base with one rock and use the ruler to balance the other two rocks on top.
Important note: Your rock sculpture should be created in a garden or indoors. Rock sculptures should not be made in nature because the movement of rocks can cause erosion.
Start a new sculpture. Select a base rock. Find a depression, chip, or bubble in the base, not much smaller than a half-inch wide and deep enough to hold another balancing rock.
Nestle the rounded end of another rock into the depression with the rock roughly vertical. Feel the direction in which it is trying to fall. Turn and twist, “walking” it around in the depression, always gently tilting opposite the direction in which it wants to fall while trying to keep the end nestled in. You will eventually feel certain positions in which the rock is less likely to fall. Use these positions to continue making fine adjustments.
Eventually your fingers will sense a point where the rock attains stability. As you loosen your hold on the rock, it will no longer fall over, but will almost maintain its vertical orientation.
Loosen your hold further, making any necessary final adjustments by feel, until you have completely let go of the rock. With luck, you can take a step back and admire your first balanced rock.
Keep going with balancing the first rock on top of your base until it can stand on its own. You might need to balance it again and again, trying out different contacts on the base, the other end of the rock, or even a different rock altogether.
Then add a second rock. If you can find a suitable contact on the second rock directly above the first rock’s balance point, all you have to worry about is trying not to disturb the first rock as you place the second. If you can’t, adjust the first rock to account for the shift in the center of gravity you caused by adding the second rock.
Once you’ve added a second rock on top of your base, keep going to see how many rocks you can balance. It all gets easier with practice, but it pays off to take it one step at a time.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Rock and Roll: Balancing River Rocks | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Discover who makes a face when they taste PTC-treated strips and learn about genetic traits.
Time needed: 60 minutes
Tip: PTC-treated and nontreated (control) strips can be purchased online.
Phenylthiocarbamide (PTC) is a chemical that has been widely used to detect genetic differences in tasting ability. PTC tastes bitter to some people based on their genetics. To others, there is no taste at all.
Tasting is not normally done in a science lab. Scientists are careful to keep their food outside of laboratory settings—this helps to make sure their food is not contaminated with potentially harmful chemicals and that their experiments aren’t contaminated by food!
But sometimes, scientist test the sense of taste! In this genetics activity, you’ll explore PTC taste sensitivity.
Get started by reading the Two Scientists’ Discoveries handout to learn the history behind the PTC test and how it was discovered.
Then think about the difference between texture and taste. This is important, because this activity is about a taste that is presented on a paper strip. The control paper has been described as having a taste, but it isn’t a taste; rather, it is the texture of the paper.
Take a control strip, place it on your tongue, move it around so it mixes with your saliva, and determine if there is a taste.
Next, take a PTC-enhanced strip, place it on your tongue, move it around so it mixes with your saliva, and determine the type of PTC taster you are: AA (you detect strong bitter taste) AB (you detect a mild bitter taste), or BB (you don’t notice any bitter taste).
Afterward, discard both the control strip and the PTC strip in the trash.
If you find out you’re an AA or AB taster, sip a drink or take a bite of food to help break down the bitter taste of the PTC.
For More Fun: Let the Tasting Begin Bingo
If you have a group of people or family members who would like to find out if they are PTC tasters, have everyone try the control and PTC-enhanced strips. Once everyone has determined if they are AA, AB, or BB, then you can see if people with the same genetics for PTC tasting have similar food preferences.
First, print the Let the Tasting Begin: Bingo sheet for everyone who would like to play.
Next, each player should write the foods they like above the diagonal of each square.
Then tell players to find other players who have the same likes they do and initial below the diagonal of each square. It is easiest to exchange cards with a person and look for a match, then initial and return the card. Each person with a match can initial only one square.
After six minutes, see who has the most bingo lines across, down, or diagonally.
Have players compare if their PTC genetics correlated with other players with the same PTC genetics.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Yuck! That Tastes Terrible: Discovering a Unique Genetic Trait | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.
Build a functional stylus that will activate a capacitive touch screen.
Time needed: 5–15 minutes
Most smartphones and tablets have capacitive touch screens. This technology lets someone interact directly with the screen using only their finger. But there is one problem with this kind of interface: dirty fingers. A stylus helps the user draw on a tablet without fingerprints, but it can be expensive, costing $10 to $30 for what is basically just a piece of metal.
Save money and solve the problem of getting touch screens dirty with fingerprints by building a simple stylus from everyday materials.
Criteria are the goals a design must meet. The criteria for this activity are:
First, gather the materials you’ll need to follow as you design a touch-screen stylus.
Next, design a pipe cleaner stylus. Fold the pipe cleaner in half, and insert the pipe cleaner into the straw so that the folded end is sticking out. Next, moisten the folded end of the pipe cleaner with water. Test the stylus by making the folded part bigger or smaller and notice differences in how it works.
Once you have designed the pipe cleaner stylus, try some of the other materials. Then test your stylus again and see how well it works!
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, BuildYourOwnTouchScreenStylus.pdf (si.edu) © 2019 Smithsonian Institution.
Use genetics to create your own creature based on physical characteristics.
Time needed: 60 minutes
Genetics is the study of heredity and the variation of inherited characteristics. Scientists study genetics by looking at genotypes. A genotype is an organism’s genetic makeup, which is determined by alleles. Alleles are the different forms a gene may have for a trait.
In this activity, you’ll use two alleles for each trait. With two alleles per trait, the genotype can be homozygous—meaning the two alleles that make up the genotype are the same—or heterozygous—meaning the two alleles that make up the genotype are different. The combinations of alleles create the phenotype, which is the organism’s physical appearance.
Alleles are dominant or recessive. Dominant alleles are the form of a gene that, when included in the genotype, are expressed in the phenotype. Recessive alleles are the form of a gene that are only expressed in the phenotype when both alleles of the genotype are recessive. For example, in this activity, fur length is a phenotype; the dominant allele is long fur (L) and the recessive allele is short fur (l). The creature has short fur only if it has two recessive alleles (l).
In this activity, you’ll create your own creature to discover the difference between genotype and phenotype and between dominant and recessive alleles for genetic traits including fur length, eye color, horn and wing shapes, teeth, and height. Then you’ll predict the inheritance of each trait in an offspring of two parents. This process is like what genetic engineers and scientists go through when designing and studying new species of plants and animals.
Part 1: Create your mother and father characteristic charts.
At the top of a sheet of paper, write “Mother.” Starting with the next line down, count 11 lines. Draw a horizontal line and write “Father” below the line. Use your ruler to draw seven vertical lines on the paper, creating eight columns.
On the first line (below “Mother”), write the eight column headings: Trait, Dominant Allele, Recessive Allele, Allele 1, Allele 2, Genotype, Homozygous Dominant/Heterozygous/Homozygous Recessive, and Phenotype.
In the first column (under “Trait”), write each of these characteristics on a line: fur length, fur color, eye color, horn shape, wing shape, wing color, feet, height, and teeth.
In the second column (under “Dominant Allele”), write: Long (L), Green (G), Purple (P), Curved (C), Dragonfly (D), Purple (R), Not webbed (W), Tall (H), and Pointed (T).
In the third column (under “Recessive Allele”), write Short (l), blue (g), Blue (p), Straight (c), Butterfly (d), Red (r), Webbed (w), Short (h), and Blunt (t). You have now created your “Mother Characteristic Chart.”
Follow the same instructions to create your “Father Characteristic Chart.”
Part 2: Determine each allele by rolling the die.
In the next part of the activity, fill in the “Allele 1” and “Allele 2” columns with the upper- and lowercase letters that correspond with the dominant and recessive alleles for each trait.
For each genetic trait, roll the die twice for the mother to get two alleles. Odd numbers will be dominant alleles. Even numbers will be recessive alleles.
Then determine the genotype; whether the alleles are homozygous recessive, heterozygous, or homozygous dominant; and lastly the phenotype.
After you’re done with the mother’s alleles, follow the same instructions to determine each allele for the father.
Then draw the mother and father creature on blank paper using the phenotypes you have determined.
Part 3: Hypothesize what the offspring of these two creatures would look like.
For the last part of the activity, use your mother and father charts to create a new characteristic chart for the two creatures’ offspring. You can determine the alleles from the parents’ charts, with Allele 1 coming from the mother and Allele 2 coming from the father.
Then determine the genotype; whether the alleles are homozygous recessive, heterozygous, or homozygous dominant; and lastly the phenotype for the offspring.
On another sheet of blank paper, draw the offspring creature based on your hypothesis.
Courtesy of the Smithsonian Science Education Center. Adapted from the WiSTEM2D, Creature Feature: A Genes and Molecular Machines Lesson | Smithsonian Science Education Center (si.edu) © 2019 Smithsonian Institution.