Warning Sign!

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Students will be able to make a warning sign about an environmental toxin in order to warn people about its dangers.

Big Idea

Warning signs are most effective when they are memorable and difficult to ignore.


Towards the end of the year I like to give students the chance to make some of their own investigations into environmental issues.  Although the lesson begins with a whole class focus on the question of the environmental dangers of nuclear waste, students ultimately get the opportunity to investigate an environmental threat that speaks to their interest.  

In this lesson, we first read an article about nuclear waste and efforts to design warning signs that could stand the test of time (i.e., will be comprehensible for as long as the nuclear waste remains dangerous).

We then watch a short powerpoint about warning signs, and how some could be misinterpreted by people of different cultures.  

Finally, students will conduct short research on an environmental danger and try and design a warning sign that effectively communicates that danger.


This lesson will most likely take more than one class period.  I would estimate between 2-3 hours of class time, but maybe more depending on how deep you want to dive into each section.

The content of the reading for this lesson (nuclear power) is a good follow up to the lessons on energy resources and the pros and cons of varying sources.  

Connection to Standards:

In this lesson, students will conduct short researchgather information from multiple sources, and acquire domain-specific vocabulary to communicate a message about the danger of toxic substances.

Warm Up: What's wrong with a bad sign?

15 minutes

I start this lesson with the attached powerpoint presentation.  Since this lesson is inherently visual, I find it's easiest to get right into looking at different warning signs rather than talking without the benefit of a visual reference.

The title slide has an interesting warning sign, so I ask students what they think it's saying.  Answers vary (and some can be pretty humorous), but most students interpret the sign to mean that boaters should be aware of the threat of collisions with a whale (which might cause passengers to be thrown overboard).

We then move on to the slide showing the standard "Surgeon General's Warning" about the dangers of smoking cigarettes.  I ask a student to read the warning and I ask students if they've seen the warning before, most say yes.

I then move to the next, very graphic warning sign and ask students which of the two signs they think more effectively communicates the dangers of smoking.  Without reservation, students say the graphic image is more effective because it shows the dangers rather than just telling them. 


We then progress through the rest of the presentation, also noting that while images can be a good way of getting a message across, they can also be confusing (the example of the large fish and the "electric" water is open to many interpretations).  We also note in the final slide that the man in the image has a wide-eyed look, but without understanding the Japanese text, it's hard to tell what he's so alarmed about.

At the end of this presentation, I ask students to answer the following questions:

  1. What's wrong with a "bad" warning sign? A: it's open to misinterpretation or it may not effectively communicate critical information.
  2. What elements are important for a "good" warning sign? A: a good warning sign should have images to show the danger being described, along with easily understood text to clarify the intent of the warning.


After this consensus has been reached, I let students know that they will be doing some research and making their own "good" warning sign later in the lesson but we will first do a close reading of an article about the challenge of making a warning sign that will remain comprehensible for thousands of human generations.

Close Reading: An alert unlike any other

30 minutes

After the brief introduction, I hand out copies of the article "An Alert Unlike Any Other" which details the challenges of making warnings for a nuclear waste site that will remain comprehensible as long as the waste remains hazardous, in this case many tens of thousands of years.

I quickly go over the instructions detailed below and then ask students to take 30 minutes of silent reading time to read the article.  This may be too much time for some more advanced readers, but without a substantial time set aside, it's more likely that my English Learners and below grade level readers won't be able to finish the reading and follow-up questions.  If you have students obviously finished ahead of time, you might want to let them begin the research they'll do in the next section.


Like previous lessons (Of Moths and Sloths, Is Overpopulation a Problem?) that employ close reading as a strategy, the first thing that I ask students to do is to underline or highlight unfamiliar vocabulary as they read the article.  This is part of a conscious attempt to help improve the general academic vocabulary of my English Learners.  Following their first reading of the article, I ask them to make a list of the unfamiliar words they identified, then choose 5 of those words and write their definitions.  Again, the reason I ask them only to define 5 words is that their list of unfamiliar words is helpful to me to see which words students may have trouble with without disincentivising their making a full list (i.e., if they have to define all the words they find unfamiliar, they will identify fewer words to avoid more work).


Following the reading, the copy of the article includes some short answer, comprehension questions for students to answer.  These questions are a mix of different levels (see the discussion of the close reading strategy in the Of Moths and Sloths lesson). 

After the 30 minutes of silent reading time are up, I ask students to go over their answers to the follow-up questions in their small groups.  During this time, I walk around to the different groups to help as needed and get a sense of where the class is at on comprehension and which groups may have good answers to share.


After about 10 minutes of small-group discussion, we debrief and answer the questions as a whole class.  If students don't volunteer their answers, I select groups to participate based on the quality of the discussions I overheard as I walked around.  Here's a quick overview of the questions and answers:

  • Why is it important that warning signs for the WIPP (Waste Isolation Pilot Plant) be easily understood by different people of different cultures?
    • The radioactive waste stored at the WIPP facility will remain dangerous far into the future.  It is hard to predict who the inhabitants of New Mexico will be far into the future because there have been multiple cultures inhabiting the location in just the last 500 years.  If the signs are only understood by modern American culture, they will not effectively communicate a danger.
  • Why would the article refer to nuclear waste as “the forever problem”?  Give specific quantitative information from the article in your answer.
    • Nuclear waste is a “forever problem” because it remains dangerous far longer than the culture that created it is likely to exist.  As the article states, “today's hazards will outlast the civilizations that created them”.  The article gives a few numbers to support this:
      • the walls surrounding the chamber storing the waste will collapse within 1,000, but “plutonium remains deadly for 250 times that long” which suggests it will be deadly for 250,000 years. 
      • In other parts of the article the author mentions that they are trying to communicate across “500 generations” which would be significantly less than 250,000 years… closer to 10,000 to 20,000 years.
      • The article also mentions a former atomic test site that had a plaque that read “this site will remain dangerous for 24,000 years”. 
  • Give at least one example from the article of a warning sign or symbolic message being misinterpreted.  Make sure to explain both the intended message and how it was misunderstood.
    • There are two main examples of this from the article:
      • In the case of the South African miners, they misinterpreted a pictograph (sequential images like a comic strip) that was intended to communicate that they should remove rocks from mine tracks.  Instead, they read the pictograph in the opposite direction and added rocks to mine tracks.
      • Another example is that tombs of pharaohs in Egypt were covered in warnings and curses, which were ignored by future generations of tomb robbers and looters that took those warnings as proof that there were riches inside.
  • Do you agree with those that say the WIPP site should be unmarked or do you think there should be a large monument with warning signs?  Explain.
    • Answers to this question will vary depending on the student, but it’s important that students arrive at an understanding of both sides:
      • An unmarked site will “fade away into the New Mexican desert” and not be uncovered.  A monument would only attract attention and invite exploration.
      • A monument will convey the importance of the danger so that future civilizations don’t accidentally penetrate the WIPP and bring its dangers to the surface.
  • Use the remaining space below or a separate piece of paper to sketch a warning that you think should go on the plaque at WIPP.  Explain your choices.
    • Answers to this may vary, of course.  The idea here is for students to have a quick sketch of a warning and be able to discuss why they made the design choices they did.  This can serve as an introduction to completing their own research and warning signs, or can be used directly if you choose to have students make warning signs specifically about WIPP. 


Once we have debriefed the questions and answers, I let students know that we will now be making our own signs, but what to do next really depends on the length of your class and how you wish to proceed.  The next section details how students can do research on an environmental hazard of their choice and make an effective warning sign. 

An alternative, however, would be to build on the work they did here and have students form groups that combine their individual ideas for a warning sign for WIPP and then making an effective sign.  This work could include them doing research into the environmental and human health effects of nuclear waste. 

Independent Practice: Making a Better Warning Sign

60 minutes

Depending on the length of your class, you may choose to have this section of the assignment take place on the day following the close reading. 

Once the debrief of the close reading has been completed, I introduce the final step in the lesson, which is for students to find an article about an environmental toxin or hazardous substance and then make their own warning sign.  The goal here is that students incorporate the lessons learned by reading the article and looking at the effective and ineffective warning signs in the powerpoint into making their own effective warning sign.

So as we begin, I first let students know the can choose to work alone or with a partner.  I then give them about a minute to decide if they're working alone or with a partner and then I ask each individual or pair of students to get a computer so that they can begin to research an environmental hazard.  If computers aren't readily available, then it might be possible to have students use their cellphones to find articles, or you might choose a few articles ahead of time and have them printed out, allowing groups to choose the article that most interests them.  


I don't have a handout describing the assignment, so as soon as groups are formed and have their supplies, I explain that their warning signs should contain the following requirements:

  1. The sign has an image
  2. The sign includes the name of the dangerous substance
  3. The sign communicates the danger associated with the substance (this can and should be achieved by a combination of images and text)

After I have gone over these simple guidelines, I write them on the whiteboard and allow students to ask any clarification questions and then begin working.  As far as supplies to make the sign itself, I ask them to use a regular sheet of blank paper and colored pencils or markers.  Some students prefer to make a sign on their computer (or even on certain apps on their smartphones) which is fine too.


This work takes at least 60 minutes, so it may be helpful to do the final "gallery walk" portion on the following class day.  One option to reduce the amount of class time devoted to this lesson would be to have the students conduct the research and find an article about a hazardous substance as homework.  In the case of my students, however, it's helpful that I be able to take the time to guide those students that are having trouble finding an appropriate article.  In the case of my students, they found articles on toxic substances such as lead, mercury, multiple pesticides, tetrachloroethylene (used in some dry cleaning), and phthalates (used in many plastic products). 

One possible modification for this lesson would be for you as the teacher to select the article for the students to use to make their warning sign.  As I mentioned in the previous section, one interesting approach could be to have them actually do a bit more research on the health effects of exposure to nuclear waste and have them design the "official" warning sign for WIPP.

Even with guidance, it's sometimes hard for students to incorporate all the lessons of effective warning signs into their finished product.  For example, this warning sign about phthalates has a great attention grabbing slogan and image, but fails to explain what about meal time can be dangerous... is the baby in danger of choking?  Food poisoning?  Something Else?

Another example is this warning sign about lead.  Although it describes why lead is hazardous, it's really just text with a picture of lipstick and hardly grabs the attention or conveys the relationship between lead and lipstick.

This second warning sign about phthalates mentions that they are found in some baby products and can affect health, but needs to be much more specific to be of any use to someone hoping to avoid phthalate exposure. 

As an example of a better warning sign, this warning sign about mercury is more effective because it has arresting images, names mercury specifically as the hazard, shows and tells its effects, and suggests actions that could be taken to avoid exposure, "ask your dentist".


Once all signs are made, we make a warning sign gallery and we take about 10-15 minutes for students to look at the work of their peers.  During this time, I encourage students to discuss their work with their peers.  I've found that this really helps students clarify their understanding of multiple environmental toxins if they can explain how the choices they made when making the sign were intended to communicate specific information.  Ultimately this becomes a bit of a "jigsaw" to expose students to more content about specific toxins than we have time to cover in class.    

Finally, students vote on the best warning sign and I award a little prize (usually something small and simple like candy) to the top group(s).  For the voting, I pass out little strips of scratch paper and have people write the name or a short description of the warning sign on the paper.  I then quickly tally up the votes and declare the winner (I like to mention the 1st and 2nd runners up too, though I usually don't have candy for them).