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Why Is Our Fruit Turning Brown?

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Why Is Our Fruit Turning Brown?

Disciplinary Core Ideas Is Lesson Plan Life Science Phenomena Science and Engineering Practices Informal Education

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.


In today's Daily DoWhy is our fruit turning brown?, families participate in a Dinner Table Discussion (see below) about the phenomenon of fruits (e.g., apples, pears, and bananas) turning brown. This sensemaking discussion has four parts:

  1. Families raise the question "Why is our fruit turning brown?" by introducing the phenomenon of fruit turning brown through observing apples (bananas, pears, and other "fleshy" fruits also work well) in different states: before slicing, after slicing, before cooking, after cooking, etc.
  2. Families ask students to explain what they currently understand about why they think fruit turns brown.
  3. Families prompt students to generate questions about why fruit turns brown.
  4. Families read an article together to find some answers to their questions about why fruit turns brown.
What Are Dinner Table Discussions (DTDs)?

This activity is called a Dinner Table Discussion (DTD). DTDs do not have to physically happen at the dinner table. Rather, they are intended to facilitate connections for the family around a discussion about science ideas wherever you may congregate for a meal. Whether you cook dinner at home or order takeout, the DTDs are centered around relevant science phenomena and raise common questions children have about the world around them. The goals of DTDs are to

(1) foster connection among the family through discussion of relevant science ideas;

(2) prompt students and their families to think about what they currently know;

(3) help students and their families ask what they want to know more about; and

(4) discover something new that moves everyone along the learning continuum of a particular science idea.

Like Daily Do’s, these types of activities are considered “microlearning experiences.” They are not intended to replace classroom science learning, and are not intended to be used as “homeschool” stand-alone science lessons. They are not intended to result in students being able to generate robust, complete scientific explanations of phenomena. Conversely, they are intended to move student thinking along the continuum of learning.

DTDs are intended to be family-style discussions, with provided parent talk-moves, that stimulate thinking among family members and move everyone along the continuum of learning. Each DTD has these components to them linked below. These components provide fertile ground for the discussion to be authentic, phenomena-driven, rooted in science, and focused on sensemaking.

If this is your first Dinner Table Discussion in the Daily Do series, NSTA recommends reading the guidance before trying your first family discussion.

Dinner Table Discussion—Guidance for Families

Dinner Table Discussions have three main components. The following guidance will support you in facilitating your family discussion.

Introducing the Phenomena and Raising the Question

Our goal is to raise a puzzling question for students that does three things: (1) prompts them to think about what they currently know, (2) makes them ask what they want to know more about, and (3) helps them discover something new that moves them along the learning continuum.

Tell me what you know....

We want to foster children in explaining what they think they understand to be true. These previous understandings are critical to exposing what they know and the questions they have. As they work to explain their current understandings, they will realize they don’t know as much as they think they do, which will spur the generation of further questions.

What questions do you have?

In developing insufficient explanations for things, students generate authentic questions that are the pathway to discovering the answer. In other words, these are our explanatory questions that if we were able to investigate, we would understand more about what we currently don’t understand. Our goal here is to generate lots of questions, but anticipate the common ones. The common questions are central to developing an explanatory idea, and we want to foster that environment by giving adult family members discussion prompts (talk moves) to facilitate the discussion for students as they work to articulate what they want to know more about.

Pursuing Common Questions

Our goal here is not to develop a robust and complete scientific understanding of a particular phenomenon. Our goal is to help students/children understand a puzzling phenomenon more deeply than they do. Learning is a continuum, and our goal with these discussions is to move students further along the continuum, not get them to the end. The objective is to stimulate thoughtful discussion that is rooted in a scientific phenomenon and a scientific explanation.

Why Is Our Fruit Turning Brown?

At one time or another, we have all looked at a piece of fruit and said, "No way I'm eating that!" It leads us to ask this question: Why do some fruits turn brown?

Have you ever left a sliced apple sitting out on the counter? What did it look like after some time had passed? Do bananas change in appearance after days have passed? Does this happen with all fruits? These are some of the questions we will explore today in our NSTA Science Daily Do.


Introducing the Phenomenon and Raising the Question

You have two options for introducing this phenomenon:

  1. Bake an apple dessert (cobbler, pie, etc.) with your children. Make observations about the apples when you peel and cut them versus when you cook them. Ask leading questions such as these:

    1. What do you notice about the apples before we cook them?

    2. What do you notice about the apples as they sit on the counter?

    3. Do you think this happens with all fruits, or just apples? Why or why not?

  2. Slice apples for a meal, but don’t eat all of them. After the meal, or longer (at least 30 minutes later), call the children’s attention to how the apples look. Ask leading questions such as these:

    1. What do you think happened to the apples?

    2. Why do they look different now compared to when we cut them?

Tell Us What You Know...

Encourage your children to explain to you what they know (or think they know) about why fruits like apples turn brown.

Ask them to “explain the science of why fruit turns brown.” Children will attempt many varieties of explanations, but our goal here is not to distinguish between right versus wrong answers or ideas. Rather, we want to foster discussion about the “how” and the “why” of fruit turning brown (which will ultimately lead to making sense of the science idea of oxidation, the chemical reaction that occurs when plant tissue is exposed to oxygen).

Accessing Prior Knowledge

Students may also draw on knowledge from previous grade levels during this part of the discussion. They may mention that cutting an apple is a physical change, while an apple turning brown is a chemical change. Distinguishing between physical and chemical changes is fundamental to observing similarities and differences of objects and comparing their properties.

Students may also describe different properties when making observations. For example, we can use the property of color to identify oxidation of fruit (the flesh turning brown after being cut). This may lead students to ask follow-up questions such as "Why doesn't the skin turn brown, too?" This could also lead students to mention that a banana peel turns brown, but an apple peel does not—and subsequently, ask why.

All of these connections to ideas and learning opportunities at previous grade levels should be encouraged by asking follow-up questions such as these:

  • “Can you tell me more about that?”
  • “How do you know that?”

What Questions Do You Have?

You can say something like this: “It sounds like we have more questions than answers. What questions do you have about why apples, and other fruits, turn brown?”

Encourage children to ask as many questions as possible that are relevant to the discussion.

Common questions could include these:

  • Does this happen with all fruits, or just apples?

  • Why does it only turn brown after you cut it or cook it? Is the reason for color change in cooking different? If so, how?

  • Why does it get soft when it gets brown?

  • Why do bananas turn brown?

  • What about avocados? Are they a fruit? If they are, why does the pit keep them from turning brown?

Pursuing Common Questions

Read the following Scientific American article (as a family or individually): "Why Do Apple Slices Turn Brown After Being Cut?" High school students will be able to read this article independently. Younger students will need more assistance.

After reading the article, ask your children the following questions:

  • What is one new thing you learned that you didn’t know before?

  • Which of our original questions did we answer in our discussion and by reading the article?

  • What other questions do you have about how foods change when cut, peeled, or cooked?

After discussing new things students learned, have students watch a time-lapse video of fruit and vegetable decomposition. Have them choose four fruits and/or vegetables to observe from the list below:

  • Tomatoes
  • Apples
  • Squash
  • Grapes
  • Onions
  • Plums
  • Peaches
  • Bananas
  • Zucchini

Students can write their observations on a piece of paper or share them orally. When you are ready, play the video below. You will stop the video at :30, 1:00, and 1:30 to talk with students about what they are noticing as their selected fruits and vegetables change over time. Ask them follow-up and clarifying questions similarly to how you did before. Those questions include, but are not limited to, the following:

  • What did you notice?
  • Why do you think that happened?
  • How do you know?
  • Can you tell me more about that?

Why Are the Bones Still Here?

Now that we understand more about how fruits and vegetables change in different conditions, it makes us wonder if other living things change in the same way. In this video, students watched fruits and vegetables (plants) decompose. Click the link below to explore more about decomposition in our Daily Do Why Are the Bones Still Here? 

NSTA Collection of Resources for Today's Daily Do

NSTA has created a Why is our fruit turning brown? 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.

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