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Why Are the Bones Still Here?

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Why Are the Bones Still Here?

Biology Crosscutting Concepts Disciplinary Core Ideas Is Lesson Plan Life Science NGSS Phenomena Science and Engineering Practices Three-Dimensional Learning Elementary Grade 5

Welcome to NSTA's Daily Do!

Teachers and families across the country are facing a new reality of providing opportunities for students to do science through distance and home learning. The Daily Do is one of the ways NSTA is supporting teachers and families with this endeavor. Each weekday, NSTA will share a sensemaking task teachers and families can use to engage their students in authentic, relevant science learning. We encourage families to make time for family science learning (science is a social process!) and are dedicated to helping students and their families find balance between learning science and the day-to-day responsibilities they have to stay healthy and safe.

Interested in learning about other ways NSTA is supporting teachers and families? Visit the NSTA homepage.

What Is Sensemaking?

Sensemaking is actively trying to figure out how the world works (science) or how to design solutions to problems (engineering). Students do science and engineering through the science and engineering practices. Engaging in these practices necessitates that students be part of a learning community to be able to share ideas, evaluate competing ideas, give and receive critique, and reach consensus. Whether this community of learners is made up of classmates or family members, students and adults build and refine science and engineering knowledge together.


Today's task explores a phenomenon many students and their families have probably seen: something that was once alive and is now decomposing. Animals living outside in the environment die every day. Why Are The Bones Still Here? engages students in science and engineering practices to figure out what happens to animals that die outside.

This task has been modified from its original design to be used by students, parents, and teachers in distance and home learning. While students could complete this task independently, we encourage students to work virtually with peers or in the home with family members.

Raccoon on Roadside

Before you begin the task, you may want to access the accompanying Why Are The Bones Still Here? Google Slide presentation.

Presentation of Phenomena (What Am I Exploring Today?)

Guidance. Students will be introduced to the phenomenon of decomposition by making some predictions using a photo. The goal is to get students thinking about why things seem to "disappear" over time. Presenting a phenomenon and asking students to make predictions about what they think happens next allows students to become invested in their learning. Making predictions creates a need to figure out if the science supports or refutes their predictions. Students want to know if their predictions are "right" and are eager to find out. This authentic engagement is a powerful learning process (unlike "learning about" and memorizing information about the processes of decomposition and being asked to state the information later).

Decomposition is a science concept that is identified within fifth grade in the NGSS. If you are working with elementary and early middle school students, it is perfectly acceptable for them to think organisms "disappear" into the ground at this point in their learning progression. It is not important for students to have a definition for decomposition before they are introduced to the process. We want students to build an understanding around the idea of decomposition first, and later on, have teachers give students the word and define it when students need it. Introducing new vocabulary in the moment when students are ready helps them build and retain vocabulary and creates a need for students to use the new word.

Presenting the Phenomenon

Have students look at the picture (slide 3). Ask them to think about what they might see if they looked at the raccoon in two days, in two weeks, and in two months. Have students create a series of pictures and explanations describing what they think they would see. Students can use their own paper to make a grid (slide 4), or you can print the student activity guide.

Our goal is to motivate curiosity and not to distinguish between "right predictions" and "wrong predictions." This task is to get students thinking about complex science ideas in a way that is engaging and moves student thinking forward. Making predictions about phenomena allows students to share ideas, ask investigative questions, and collect evidence that will support, or not support, their predictions.

After students have made their predictions, prompt students to think about what the raccoon might look like if it was on a different surface. How about if it was really hot outdoors or freezing cold? Have students share their ideas with you or someone else in the house or classroom.

Investigative Questions (What Questions Do I Have About What I Just Saw?)

Investigative questions are common questions kids may ask after they are introduced to the phenomena. Although questions may vary, many students are curious about what happens to dead things.

Have students write down or share any questions they are wondering about this: "Why do dead things seem to disappear over time?"

Guidance. It is important to allow students time for thinking. You can also refer them to the ideas they have recorded on their prediction page. Many students have ideas and questions, but need time to formulate their idea or question into words. Some students may also benefit from writing things down first before they share. As adults, we may be tempted to give them questions we feel might be important to explore. However, we need to refrain from this and allow our students to practice asking their own questions.

Common Questions (slide 5)

  • Do other animals eat the dead animals?
  • Do people come to and clean up the animals?
  • Does the sun make them dry up?
  • Could the wind just blow them away?
  • Does rain make them seem to melt into the ground?

After they have shared their questions, ask them what ideas they have about how to figure out what happens to animals that die outside. What could they investigate to gather evidence to support their predictions?

Many times students will want to "collect" an animal from outside and watch what happens. Collecting an animal from outside is not something we can do in a classroom (or living space), so we will do the next best thing: Watch a time–lapse video clip.

My Observations (What Observations Did I Make That Help Me Answer My Questions?)

(Slide 6) Watch the time-lapse video of the badger (below) and have students write down what they notice and wonder as they watch. (Slide 7)

Guidance. Many times it is beneficial to allow students to watch the video a few times. It is recommended to show the video all the way through without stopping first, then have students document what they notice and wonder. Then show the video a second time, stopping periodically to have students add to their chart.

To document what they notice and wonder, you can print page 1 of the student guide here, or just have them take notes on a piece of paper.

Observations Continued...

What did we observe in the video that surprised us?

Many kids have ideas about what happens to animals as they decompose, but they don't really know what happens. Some "noticings" that students are surprised about are (slide 8) these:

  • The badger seems to get bigger first.
  • The hair just blows away.
  • The bones are still there.
  • It takes a really long time for the badger to decompose.
  • There are white things that come out of it.

Guidance. It is important that you let the students tell you what they notice and to avoid pointing out the things you notice as the adult. The goal here is to allow students to practice making careful observations. If your student is struggling to make observations, use question prompts to guide them instead of stating what you see. However, as students watch the video, you may want to remind them to notice the date at the bottom of the screen.

Checking Our Predictions

Now that we have a little more information about what happens to dead things over time, let's look at our original predictions (slide 9). Have students compare their predictions to what they saw in the video. What observations from the video supported their predictions? What things from the video did not support their predictions?

Many students will predict that in two months, that raccoon will be nothing but bones. The video does help support this idea that eventually only bones will be left. However, have them think about the timeline from the video.

Ask students to think about the following:

  • How much time did it take that badger from the video to disappear?
  • Do they think this raccoon would take the same amount of time?
  • Do all organisms (plants and animals) take the same amount of time to disappear?
  • Have students share their ideas and engage them in a conversation about an animal's size versus the time it takes the animal to disappear.

Guidance. Most students will equate making predictions with guessing. However, predictions are more than just a random guess. Although students may not know exactly what happens in this (or other) situations, we want them to base their predictions on prior knowledge. When thinking about this particular phenomenon, kids may express thoughts from a variety of experiences, such as these:

  • seeing an animal outside that has died;
  • noticing that plants turn brown and wither, or leaves fall off and start to go back into the soil;
  • we do not eat the bones from chicken, beef, or fish; and
  • dogs chew on bones, but don't usually eat the bone.

The goal when asking students to make predictions is to activate their prior knowledge and get them thinking about how things they already know could help us explain something new.

Answering Our Initial Question

Have students return to the Daily Do question "Why are the bones still here?" and have them share their ideas about why nothing is left but the bones (slide 10).

At this point, possible student answers may include these:

  • Other animals don't eat the bones.
  • The bones are kind of heavy, so they just stay there.
  • Most of the animal is soft, so it decomposes faster so just the bones are left.
  • Bones are hard, like rocks, so it takes a long time for them to go away.

If the word decomposition has not come up yet, this would be a good time to introduce the new vocabulary word to your students. Now we can give the process of "disappearing" a name; we call it decomposing. Students will figure out more about the process of decomposition as they continue to figure out what happens to organisms when they die.

Next Steps

(slide 11) Once students have evaluated their predictions, have them share what might change in their model to make their prediction more accurate. At this time, we can also have a discussion about the process they witnessed in the video. Now that they know a little more about what happens when something decomposes, what other questions would we need to answer to explain how decomposition happens? What would students have to figure out about what they have seen in the video so they can explain the process?

Possible Student Questions to Investigate

  • What are the black things crawling on the badger?
  • What happens to the parts that don't get eaten?
  • Why does the badger seem to get bigger before it decomposes?
  • What are the white things that came out of the badger?

Guidance. This Daily Do is not intended to result in students being able to generate a robust, complete scientific explanation of decomposition. Conversely, it is intended to move student thinking along the continuum of learning, to get them thinking about process. This lesson is meant to activate students' prior knowledge about everyday phenomena and to help them figure out what they could continue to investigate to create an explanation about the process of decomposition.

NSTA Collection of Resources for Today's Daily Do

NSTA has created a Why Are The Bones Still Here? collection of resources to support teachers and families using this task. If you're an NSTA member, you can add this collection to your library by clicking Add to My Library, located near the top of the page (at right in the blue box).

Check Out Previous Daily Dos From NSTA

The NSTA Daily Do is an open educational resource (OER) and can be used by educators and families providing students distance and home science learning. Access the entire collection of NSTA Daily Dos.


This Daily Do is inspired by and uses materials from the Why Do Dead Things Disappear Over Time? storyline created by Next Gen Storylines. Next Gen Storylines is an open-source resource that can be used by parents and teachers to implement student-driven learning.

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