Any time I can integrate science and Halloween/Fall – I’m a happy girl! Top it off with using pumpkins? I’m over the moon! Today, I’m sharing an engaging and effective way to integrate a fun fall twist into your Science curriculum. Your students will love this pumpkin science investigation and you will love how directly it correlates to physical science standards. Win-win!

I created this resource to use in my 4th Grade classroom during our Physical Science Unit. We used pumpkins to discover, study, and discuss physical properties of matter. We then continued our study into physical vs. chemical changes. This investigation can last between 1-10 days (or more), depending on how you structure the activities.

We used small pumpkins to investigate the physical properties of the pumpkin. Students worked in groups of 2-4 to investigate size, mass, color, shape, texture, hardness, and density of the pumpkin.

We used a large class pumpkin to investigate physical vs. chemical changes. We also used the large pumpkin to discuss the physical properties of the inside of the pumpkin, such as smell.

Let’s walk step-by-step through the investigation.

What You Will Need: 

  • small pumpkins (1 per each group)
  • 1 large pumpkin for class observations
  • 1 leaf (per group)
  • 1 rock (per group)
  • pan balance (1 per group)
  • tape measure (1 per group)
  • large container filled with water 
  • Science notebooks

Physical Properties of a Pumpkin

First, discuss physical properties. You can model this whole group with the large pumpkin OR discuss the properties, then have students identify the properties with their small pumpkins in their group. Students can jot notes in their Science notebook for each property on the pages included in this Pumpkin Science Investigation.


I found that it was pretty much impossible to cut the small pumpkins for each group, so we described the smell of the large pumpkin.

Pumpkin Science Investigation


We used a pan balance to measure the mass of the small pumpkins.

By all the hands trying to measure at the same time, you can see how excited and engaged students were in this investigation. 🤣

Size, Color, Texture, Hardness, & Shape

Students used the tape measure to measure the distance around the pumpkin. They recorded their observations about the color, texture, hardness, and shape on the pages inside their Science notebook. I intentionally bought different sizes, textures, shapes, and colors of pumpkins so that students could see (in real life) that not all pumpkins are orange and round.

Sink or Float? (Density)

Students used the leaf, rock and pumpkins to see which items would sink or p

Physical vs. Chemical Changes

Using the large pumpkin for the class allows you to also teach physical vs. chemical changes. This is a great introduction to this concept if the timing works out for your scope and sequence. Even when it doesn’t necessarily align to what I am teaching, I DO use the rotting pumpkins part of this as an ongoing investigation in my 4th grade classroom because it reinforces the idea of a physical vs. chemical change. If it comes later in the year, my students already have a solid background with this concept.

Use the notebook chart to discuss physical vs. chemical changes. Make sure you cut the lid of the pumpkin BEFORE you bring it in front of your students. We don’t need any horror movie situations and you can avoid any other drama carving a pumpkin might cause.🎃 Discuss how cutting or carving the pumpkin is a physical change.

To see the chemical change, conduct an ongoing observation (more information below). Throughout the days of the ongoing observation, have students record their daily observations in their Science notebook.

Pumpkin Science Investigation

These two anchor charts can be used to help students identify physical changes and record their thinking during the class or group discussion.

See, Think, Wonder 

Students record what they SEE. What can they observe with their 5 senses? Just the facts. Then, they record what they THINK. This is an inference, conclusion, or theory-thinking like a scientist. Finally, they WONDER by asking questions about what might happen or dig deeper with their scientific thoughts. We used this chart to discuss what might happen over the next few days/week with the pumpkin. 

Rotting Pumpkins (Chemical Changes)

This is the fun part! Be sure to check your school/district policy about having rotting pumpkins in your classroom and don’t keep it too long. It can become toxic indoors, especially for students with allergies. If you have an outdoor area, this would be ideal because the pumpkin can naturally decompose into the ground. We ended up observing a pumpkin that another teacher’s son brought in from a pumpkin contest. It just got more attention than our original pumpkin, so I just went with it.

Each day have students record their observations of the pumpkin rots. (These are the final days of our pumpkin.)

There you have it! I hope you enjoy this activity with your students. You can grab all the printable notebook charts and activities in my website shop or TpT Shop.

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You might also be interested in the TLL Membership that gives you access to hundreds of teaching resources for grades 3-5.

Happy Teaching!

🖤- Jessica