# data[].attributes.headline
If students want to make their presentation a Prezi, it might 

# data[].attributes.subject
If students want to make their presentation a Prezi, it might 

# data[].attributes.attachment_link.readable_text
Summary Students are introduced to the concept of engineering biological organisms and studying their growth to be able to identify periods of fast and slow growth. They learn that bacteria are found everywhere, including on the surfaces of our hands. Student groups study three different conditions under which bacteria are found and compare the growth of the individual bacteria from each source. In addition to monitoring the quantity of bacteria from differ conditions, they record the growth of bacteria over time, which is an excellent tool to study binary fission and the reproduction of unicellular organisms.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

The word bacteria often brings up negative connotations related to illness and disease. However, many bacteria are beneficial to humans and useful (even essential), as well. Biological, environmental and biochemical engineers must have a thorough understanding of bacteria in order to use these organisms in devising new treatments for diseases, better oil spill clean-up, and the production of alternative energy forms. Biochemical engineers genetically modify the DNA in bacteria to produce "designer proteins," and proteins to treat diseases, such as cancer or to act as new materials enabling the conversion of solar energy to useable electricity. Bacteria are also used by environmental engineers as an ecologically-friendly way to digest (literally, to eat) the carbohydrates in oil from off-shore oil spills. Knowledge of the growth rates of bacteria is essential for these types of engineers in order to use the microorganisms in valuable ways for human and ecological life.

Learning Objectives

After this activity, students should be able to:

Describe the potential positive and negative roles bacteria play in our lives.

Determine, based on data analysis, the best way to keep bacteria off our hands.

Plot data and determine their significance.

Explain generally where bacteria can be found.

Describe the conditions and requirements that bacteria need to survive.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

Click to view other curriculum aligned to this Performance Expectation

This activity focuses on the following Three Dimensional Learning aspects of NGSS:

Science & Engineering Practices

Disciplinary Core Ideas

Crosscutting Concepts

Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors. In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. Growth of organisms and population increases are limited by access to resources.

NGSS Performance Expectation

Click to view other curriculum aligned to this Performance Expectation

This activity focuses on the following Three Dimensional Learning aspects of NGSS:

Science & Engineering Practices

Disciplinary Core Ideas

Crosscutting Concepts

Phenomena that can be observed at one scale may not be observable at another scale. Engineering advances have led to important discoveries in virtually every field of science, and scientific discoveries have led to the development of entire industries and engineered systems.

Plan and conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells. (Grades 6 - 8) More Details
View aligned curriculum

Do you agree with this alignment?

Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function. (Grades 6 - 8) More Details
View aligned curriculum

Do you agree with this alignment?

Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem. (Grades 6 - 8) More Details
View aligned curriculum

Do you agree with this alignment?

Suggest an alignment not listed above

Materials List

Each group needs:

3 Petri dishes (10 cm diameter) filled with tryptic soy agar; see preparation instructions in the Procedure section

3 cotton-tipped swabs (1 per sample)

Where's My Bacteria? Worksheet, one per student

assorted colored pencils and/or markers

To share with the entire class:

Worksheets and Attachments
Visit [www.teachengineering.org/activities/view/nyu_bacteria_activity1] to print or download.

Introduction/Motivation

Have you ever noticed blobs of mold or strangely colored microorganisms around your house? These strange organisms might have shown up in suspicious looking food or in a pink ring around the water in a (dirty) toilet bowl. Well, microorganisms are all around us, and we can even study how quickly they grow.

At the end of this activity, you will know what specific factors influence the growth of microorganisms, such as bacteria, and know what effects these various factors have on bacteria. People generally think that bacteria are bad for us or dirty, but in reality, many different types of bacteria are essential and beneficial to us.

When we study bacteria closely, we find that they fascinating organisms. They have special features that make them ideal organisms for scientists and engineers to use in a wide ranage of applications ranging from medicine to environmental and energy engineering. One of these features is that bacteria grow very quickly. On average, bacteria reproduce every 20 minutes, which each bacterium does by splitting into two identical copies of the parent. That means that one bacterium turns into two, those two split into four, which then split into eight, and so on. If each split takes only 20 minutes, it does not take long before we have millions of bacteria. Scientists use this knowledge to their advantage to grow large quantities of these organisms for a variety of purposes. Another important feature of bacteria is that they do not need much to thrive: all they need for growth is air, water and a carbon source (such as sugar). Different strains of bacteria have adapted to survive in very harsh climates, such as high altitudes, deep in the ocean, and at very cold or hot temperatures. All of these features allow scientists and engineering to use them in a wide range of applications.

Not only do these organisms affect the exterior and interior of our bodies, but bacteria such as E. coli are also used by biochemists and engineers to produce important proteins for therapeutic purposes through biosynthesis. Biosynthesis refers to the process by which cells, such as bacteria, put together simple molecules to make more complex ones. It is the process of biosynthesis that E. coli use to make new proteins that pharmaceutical companies then sell as treatments for various illnesses.

Engineers also add bacteria to biofuel to create useable energy and remove waste from fermentation by-products while generating electricity. And, scientists and engineers modify different types of bacteria to act as clean-up agents for oil spills: the bacteria are able to break down oil compounds to simplify its removal from seas and oceans.

This activity demonstrates that bacteria are found everywhere and that it is difficult to kill bacteria, even after washing our hands and applying antibacterial hand sanitizer. Using image processing software called ImageJ®, you will estimate how many bacteria collected from different surfaces grow over time.

Procedure

About the Activity

Through this activity, students study three different conditions under which bacteria are found and compare the growth of the individual bacteria from each source: 1) an unwashed hand, 2) a hand washed with soap and water, and 3) a hand sanitized with antibacterial hand gel. Students take swab samples of one of their team member's hands under each of the three conditions and streak the swabs on Petri dishes containing agar gel, which supports bacterial growth. After a week, the three samples in Petri dishes show growth, giving students an opportunity to quantitatively compare the amount of bacteria growing from each test condition.

Quantitative analysis of these samples, via photographs taken of the Petri dishes at different time points, is conducted by analyzing the images through special imaging software. In addition to monitoring the quantity of bacteria from the different conditions, students also record the growth of bacteria over time, which is an excellent tool to study binary fission and the reproduction of unicellular organisms.

Background

Bacteria are unicellular organisms that reproduce by a process called binary fission, meaning that each singular bacterium splits into two after its genetic material is duplicated. This method of replication is asexual, since the bacterium does not need a partner's genetic material to be able to reproduce. Bacteria are prokaryotic organisms, which mean they are cells that have no nucleus. The time it takes for bacteria to complete binary fission, on average, is 20 minutes. In order to grow, bacteria need three things: water, air and a carbon source (sugar, for example). Most bacteria have optimal growth at a temperature of 37 °C, or 98.6 °F (the temperature of a healthy human body). Bacteria can grow in a wide range of different environments, and since they do not carry out photosynthesis, they can grow with or without sunlight.

Researchers use two methods to count bacteria:

Shine a light through a liquid media with bacteria growing, and measure how much light is scattered by the sample. More scattering means more bacteria.

Use a cell counter, which uses software connected to a microscope, to look at a sample of media with bacteria. The software counts the number of bacteria.

Before the Activity

Gather materials and make copies of the worksheets and pre/post assessments.

Prepare TSA plates: Preparation instructions: add 10 g tryptic soy agar (TSA) to 250 ml water in a microwaveable container. Microwave the solution for about 3 minutes (until boiling). Pour the hot solution into the Petri dishes, so that you just cover the bottom completely. Let Petri dishes stand for 20 minutes while the agar solidifies. (Note: 250 ml TSA solution will make 30 Petri dishes; adjust quantities appropriately depending on how many dishes you want to prepare.)

Label three Petri dishes for each group by using a marker to write the group number/name and class on the lids. Also, clearly mark the following on each of the three lids: unwashed, washed, sanitized.

With the Students

Figure 2. Students streak plates with sample bacteria found on their hands.

Inform students that samples of bacteria will be collected from the surface of their hands and the bacterial will be grown over time. To reduce experimental error, take samples from only one student's hand, but under three different conditions:

unwashed hand

hand washed with soap and water

hand sanitized with antibacterial hand gel

Part I: Streaking the Plates

1. Instruct students to choose one student in each group for each of the following roles: Sample Student (provides the hand samples), Swabber (collects the swabbing samples), the Supervisor (makes sure the correct Petri dish is being used) and the Washer (oversees the washing and sanitizing of the sample student's second hand). Note: To reduce experimental error, it is important to have all samples come from the same person.

2. Hand out three pre-labeled Petri dishes to each group; ask students to notice how each lid is labeled.

3. Direct students to begin with the "unwashed" Petri dish. From the Sample Student, a second group member, the Swabber, should gently rub a cotton swab on the surface of that student's palm. Be sure the Swabber does not lay down the cotton swab.

4. The Supervisor, a third group member, should open the "unwashed" Petri dish containing agar.

5. The Swabber should gently rub the cotton swab sample taken from the unwashed hand back and forth on the agar. Remind Swabbers to be very careful not to apply too much pressure when doing this, so as to not tear the agar.

6. The Supervisor should close the Petri dish.

7. Instruct the fourth group member, the Washer, to carefully wash one hand of the Sample Student's hands with soap and water. (Note: Groups should approach the sink one at a time to avoid cross contamination.)

8. The Swabber and Supervisor should repeat steps 4-6 for this hand; being careful to streak the dish labeled "washed."

9. Finally, the Washer should apply hand sanitizer to the Sample Student's other hand (the hand that was not washed in the previous step). Allow the hand to air dry until all gel has evaporated.

10. Instruct students to repeat Steps 4-6 for this hand, except being careful to streak the plate labeled "sanitized" this time.

Part II: Data Acquisition
If computing resources are limited, collect the data and demonstrate to the class how this part of the activity is done.

If computing resources permit, and students are able to process the images themselves, present the following ImageJ® instructions to them.

1. Take a photo of each plate approximately four days after streaking. Save each file to your computer, naming it descriptively (such as, "unwashed_day4.jpg" or "sanitized_day5.jpg").

Figure 3. ImageJ® analyzes the size of the circular black particles (colonies) and expresses it as a fraction of the area analyzed.

2. Open the ImageJ® software.

3. Select File > Open from the drop down menu.

4. Select the image file to be analyzed.

5. Trace a line over your scale bar. Select Analyze > Set scale. Fill in the "Known distance" box for the length of your scale bar, and set the "Units." Tracing the line over the scale bar tells ImageJ® how many pixels correspond to a given distance (the length of your scale bar). This enables the software to determine the size, and hence area, of different features that appear in your image.

6. Click Image > Adjust > Threshold. For the Threshold Color, select B&W. Adjust the Hue, Saturation, and Brightness levels until you obtain your bacterial colonies in black and the background agar in white.

7. From the toolbar, select the "Circle" image. Draw a circle around the edge of the Petri dish to define the precise area from which the software will measure the bacteria.

8. Next, from the Analyze menu, select "Analyze Particles." Set "upper limit" size to 4 cm² (generally bacterial colonies would not be larger than 4 cm²). "Circularity" should be 0-1, and select Nothing from the "Show" drop down menu. Select "Summarize" from the checklist. Click OK.

9. The Summary window opens and provides data on the area of the Petri dish that is covered in bacterial colonies. This data is found under the column "Total Area," and is given in square units of what you entered in step 5. The Summary window also displays the "Area fraction." Students may record the area fraction (given as a % of the total area measured) and use this as their data for the amount of the Petri dish covered by bacteria.

10. If you chose, you can save the adjusted photo by File > Save As > "new name."

Vocabulary/Definitions

aerobic respiration: Respiration that requires oxygen.

anaerobic respiration: Respiration that does not require oxygen.

bacteria: A unicellular microorganism with no nucleus.

colony: A visible cluster of bacteria.

eukaryotic: A cell that has a nucleus.

fission: One cell divides into two, which is how bacteria reproduce.

photosynthesis: Converting light energy into chemical energy to fuel an organism's activities.

prokaryotic: A cell that lacks a nucleus.

Assessment

Pre-Activity Survey - Instruct students to individually complete Pre-Assessment Bacteria Survey s. Review their answers to gauge their comprehension.

Worksheet - Have students use the Where's My Bacteria? Worksheet to guide the activity. They should work on the worksheets within their groups only, no sharing of answers across groups. And, each student should complete his/her own worksheet. Review their data, graphs and answers to gauge their mastery of the subject matter.

Post-Activity Survey - Instruct students to individually complete Post-Assessment Bacteria Survey s. Review their answers to gauge their depth of comprehension.

Safety Issues

As soon as the plates have been streaked and the Petri dish lid replaced, apply two pieces of tape to keep the lids connected; however any closure should not be made air-tight.

Keep the Petri dish plates away from students until the time of data analysis. No student, at any time, should touch the agar or the bacteria. When taking pictures, open the lid briefly and replaced it immediately.

When the activity is complete and pictures have been taken of all samples, immediately discard the Petri dishes in a trash container that is securely away from the student population.

Troubleshooting Tips

For optimal bacterial growth, place the Petri dishes in well-ventilated warm locations, between 22 ⁰C (72 ⁰F) and 37 ⁰C (99 ⁰F.)

Activity Scaling

For lower grades, omit analysis of the images and simply examine the bacterial growth by eye. Compare the three samples to each other to obtain a relative quantization of the amount of bacterial growth in the Petri dishes.

For upper grades, take images of the samples more frequently for quantifiying and plotting. Expect the resulting plots to show an exponential growth of bacteria over time. Mathematically fit the data exponential curves and perform regression to determine how closely the experimental data matches the theoretical predictions.

Copyright © 2013 by Regents of the University of Colorado; original © 2012 Polytechnic Institute of New York University

Contributors Jasmin Hume; Janet Yowell

Supporting Program AMPS GK-12 Program, Polytechnic Institute of New York University

Acknowledgements

This activity was developed by the Applying Mechatronics to Promote Science (AMPS) Program funded by National Science Foundation GK-12 grant no. 0741714. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Additional support was provided by the Central Brooklyn STEM Initiative (CBSI), funded by six philanthropic organizations.

Last modified: January 23, 2021

# data[].attributes.attachment_link.description
Students are introduced to the concept of engineering biological organisms and studying their growth to be able to identify periods of fast and slow growth. They learn that bacteria are found everywhere, including on the surfaces of our hands. Student groups study three different conditions under which bacteria are found and compare the growth of the individual bacteria from each source.

# data[].attributes.attachment_link.readable_text
The COVID-19 outbreak that began in China has sickened thousands worldwide.

By Monday, the novel coronavirus outbreak in the United States had grown to at least 4,200 cases in 49 states, the District of Columbia and Puerto Rico. There are outbreak clusters in New York , Washington State and California, according to Johns Hopkins University, which is tracking reports and confirming them with local health departments.

The number of cases in the U.S. and worldwide is the subject of some debate, as testing has been rolled out unevenly and the criteria for diagnosis (through clinical means or a lab test) has varied from country-to-country.

For more information on COVID-19 cases in your state, check your state's health department website, listed below. The U.S. Centers for Disease Control and Prevention maintains nationwide statistics, but they are not updated as frequently. Information from Johns Hopkins University is not independently verified by ABC News.

Despite the growing number of lab-confirmed cases in the U.S., the figures pale in comparison, for instance, to the seasonal flu, which kills an estimated 12,000 to 61,000 people per year and affects between 9 million and 45 million people in the country alone, according to the CDC.

What is unknown is how deadly coronavirus, which has no treatment at this point, is compared to the flu or how serious its effects are for those who are sickened but do not die.

Of those cases in the U.S. (pictured above), at least 48 were diagnosed in individuals who were repatriated to the United States on government charter flights from Wuhan, China, and from the Diamond Princess cruise ship. But many others are cases of unknown origin, or potential community spread, where there is no known nexus to travel.

Tracking novel coronavirus worldwide

Meanwhile, the virus, officially known as COVID-19, has spread to dozens of countries in regions around the world.

The novel coronavirus outbreak began in Wuhan, China, in late December, and has since sickened at least 179,165 people worldwide, including hundreds in the United States, and killed thousands, primarily in mainland China and Italy, according to data from Johns Hopkins. A least 78,078 people have already recovered, JHU said.

Check your state's health department for the latest COVID-19 cases

By Monday, the novel coronavirus outbreak in the United States had grown to at least 4,200 cases in 49 states, the District of Columbia and Puerto Rico. There are outbreak clusters in New York , Washington State and California, according to Johns Hopkins University, which is tracking reports and confirming them with local health departments.

The number of cases in the U.S. and worldwide is the subject of some debate, as testing has been rolled out unevenly and the criteria for diagnosis (through clinical means or a lab test) has varied from country-to-country.

For more information on COVID-19 cases in your state, check your state's health department website, listed below. The U.S. Centers for Disease Control and Prevention maintains nationwide statistics, but they are not updated as frequently. Information from Johns Hopkins University is not independently verified by ABC News.

Despite the growing number of lab-confirmed cases in the U.S., the figures pale in comparison, for instance, to the seasonal flu, which kills an estimated 12,000 to 61,000 people per year and affects between 9 million and 45 million people in the country alone, according to the CDC.

What is unknown is how deadly coronavirus, which has no treatment at this point, is compared to the flu or how serious its effects are for those who are sickened but do not die.

Of those cases in the U.S. (pictured above), at least 48 were diagnosed in individuals who were repatriated to the United States on government charter flights from Wuhan, China, and from the Diamond Princess cruise ship. But many others are cases of unknown origin, or potential community spread, where there is no known nexus to travel.

Tracking novel coronavirus worldwide

Meanwhile, the virus, officially known as COVID-19, has spread to dozens of countries in regions around the world.

The novel coronavirus outbreak began in Wuhan, China, in late December, and has since sickened at least 179,165 people worldwide, including hundreds in the United States, and killed thousands, primarily in mainland China and Italy, according to data from Johns Hopkins. A least 78,078 people have already recovered, JHU said.

Check your state's health department for the latest COVID-19 cases

# data[].attributes.attachment_link.keywords[]
centers for disease control and prevention

# data[].attributes.attachment_link.title
Coronavirus map: Tracking the spread in the US and around the world

# data[].attributes.attachment_link.description
The COVID-19 outbreak that began in China has sickened thousands worldwide. By Monday, the novel coronavirus outbreak in the United States had grown to at least 4,200 cases in 49 states, the District of Columbia and Puerto Rico.

# data[].attributes.attachment_link.readable_text
Coronavirus (or, as doctors and scientists call it, COVID-19) has been part of everyone's life since mid-March 2020, when most schools, businesses, and communities quickly changed how they operated to prevent the spread of the virus. Because the disease infected a large number of people all over the world, experts call this a pandemic.

For over a year, many kids attended school at least partly from their houses; their parents might've worked from home, too. This was all to avoid catching the virus from other people outside the home.

Lots of people helped their neighbors throughout the pandemic. First responders, like healthcare workers, police officers, and firefighters, kept people healthy and safe; essential workers such as grocery store employees, delivery drivers, and postal workers worked in-person to make sure other folks had what they needed to live.

Nearly 190 million people in the world have been infected by COVID-19, and more than four million people have died. But the good news is that the number of people getting the virus in the United States is going way down, thanks to testing, vaccines, and other preventative measures, like wearing masks and social distancing.

Here are answers to some questions you might still have about coronavirus.

So ... what is COVID-19? And what's a "coronavirus?"

The term "coronavirus" actually refers to a family of viruses that causes many different types of diseases, including the common cold. COVID-19 is a "novel coronavirus," which means it's a new disease unfamiliar to scientists and doctors. Its name is actually a mash-up of three words: CO stands for "corona," which means "crown" in Latin, and the viruses are named for the crown-like spikes on their surface; VI stands for "virus"; and D is for "disease." The "19" comes from the year 2019, when the disease was first detected.

How did COVID-19 start?

Scientists don't know the exact origin of COVID -19, and they might never have all the answers. But they do know that some diseases start in animals before spreading to humans. These types of diseases are called zoonotic (pronounced zoh-uh-NAH-tik). Cows, bats, and camels are among the animals that have spread diseases to humans in the past. The COVID-19 disease is also zoonotic, with the first cases popping up in December 2019 in Wuhan, China. The affected humans were all connected to a nearby market that sold live animals.

How does someone catch COVID-19?

COVID-19 can be transmitted by little droplets from coughs or sneezes, which is why doctors say unvaccinated people should wear masks when they're indoors or close to others. According to the Centers for Disease Control and Prevention (CDC), there's no evidence that a dog, cat, or any other pet can transmit COVID-19. But more studies are needed to understand how COVID-19 could affect different types of animals.

How can I protect myself?

Kids older than 12 can now get the Pfizer COVID-19 vaccine. For older kids who aren't vaccinated, as well as kids 11 and younger, research shows that taking small steps-like staying six feet (about two arm lengths) from others, wearing face masks that cover the mouth and nose, washing hands often, and seeing friends outside-can make a big difference in stopping the spread of the virus. (Vaccines for kids under 12 are expected to be available later in 2021.)

Learn how vaccines work and why they're so effective.

OK, but what happens if I do get it?

Most people-including kids- who catch COVID-19 get better, and their illness is usually mild. But if you do catch COVID-19, you might have a dry cough, a fever, and shortness of breath. But just like when you've had a cold, the best treatment is to stay in bed-and away from anyone who might catch it from you. (Like your grandparents! Older people are more at risk for catching and getting sick from COVID-19.) You might also not even know you have it, so keep washing your hands and wearing a mask, just in case. Masks work best when everyone wears one.

Researchers expect that as more people are vaccinated and become immune to COVID-19, the number of cases will continue to go down. Immunity to the virus means the body can fight it off and won't spread it to another person. When enough people are immune to COVID-19 so that the illness is no longer a serious threat, that's called herd immunity. Experts say that for herd immunity to work in a community, between 75 and 85 percent of people need to be vaccinated. Almost 60 percent of Americans are fully vaccinated, depending on where you live: Some places are higher, and others are lower.

The majority of new cases in the United States are in unvaccinated people. They can also transmit the coronavirus to others, which is why the CDC recommends they still wear masks indoors and at crowded outdoor events.

What about school?

The latest guidelines from the CDC say that students and teachers who are fully vaccinated-meaning it's been two weeks since their second COVID-19 shot-can be in class without masks. For students too young to get the vaccine, the recommendation is to keep doing what you've been doing in school: wear masks and social distance. Scientists say that keeping just three feet indoors in school is enough to keep kids safe.

This story has been updated with new information about vaccines for children.

# data[].attributes.attachment_link.description
Coronavirus (or, as doctors and scientists call it, COVID-19) has been part of everyone's life since mid-March 2020, when most schools, businesses, and communities quickly changed how they operated to prevent the spread of the virus. Because the disease infected a large number of people all over the world, experts call this a pandemic.

# data[].attributes.attachment_link.title
Criteria for Selecting a Newsworthy Story

# data[].attributes.headline
Experiment about if hand washing and sanitizer work

# data[].attributes.subject
Experiment about if hand washing and sanitizer work

# data[].attributes.attachment_link.description
How about Creating your own Graph? Really. See for yourself; it’s easy to create and even print your own graphs and charts

# data[].attributes.attachment_link.description
Explore our NEW Text Set: Celebrating Black History and Voices!

# data[].attributes.headline
For the Entry Event  or a way to engage interest,  we can use Poll Everywhere to have kids answer some survey questions about their health habits in school. 

# data[].attributes.subject
For the Entry Event  or a way to engage interest,  we can use Poll Everywhere to have kids answer some survey questions about their health habits in school. 