Science · 1st Grade · Properties of Materials · Weeks 19-27

Making and Unmaking Simple Changes

Students explore simple changes to materials that can be easily undone (like bending paper) and those that are harder to undo (like tearing paper).

• Common Core State Standards
• 2-PS1-4

About This Topic

In first grade science, students explore what happens when they make simple changes to materials and whether those changes can be reversed. Standard 2-PS1-4 asks students to investigate what happens when different materials are bent, torn, folded, cut, or broken, and to distinguish which changes are easy to undo from those that are permanent. When you bend a sheet of paper and flatten it back out, the paper returns to roughly its original form. When you tear that same paper, you cannot make it whole again without additional materials.

This distinction between reversible and irreversible changes builds an early understanding of matter and its properties. Teachers in the US often connect this topic to everyday objects students already handle, making abstract concepts concrete. Sorting activities, comparing folded versus torn paper, and drawing "before and after" illustrations help students build the vocabulary (bend, fold, cut, tear, break) needed to describe these observations.

Active learning is especially effective here because the changes are immediate and tangible. When students manipulate materials themselves and sort their results, they develop a personal evidence base rather than simply accepting the teacher's description.

Key Questions

1. Describe what happens when you bend, tear, or cut a material.
2. Compare changes that are easy to undo with changes that are not.
3. Predict if a simple change to a material can be easily put back the way it was.

Learning Objectives

• Classify changes made to common materials as reversible or irreversible.
• Compare the outcomes of bending, tearing, folding, cutting, and breaking a given material.
• Predict whether a specific change made to a material can be easily undone.
• Explain, using descriptive vocabulary, what happens to a material when it is bent, torn, or cut.

Before You Start

Observing Properties of Objects

Why: Students need to have experience observing and describing basic properties of objects, such as shape and texture, before they can describe changes to those properties.

Sorting Objects by Properties

Why: This topic requires students to sort changes into categories (reversible/irreversible), building on their ability to sort objects based on observable characteristics.

Key Vocabulary

bend	To curve or force something into a different shape without breaking it. The material can often be straightened again.
tear	To pull apart or rip something forcefully. This often creates permanent damage that cannot be easily fixed.
fold	To bend something over on itself so that one part covers another. This change is usually easy to undo.
cut	To divide something using a sharp tool. This can create permanent changes, like making a piece of paper smaller.
reversible	A change that can be undone, returning the material to its original state. For example, unfolding a piece of paper.
irreversible	A change that cannot be undone, making it difficult or impossible to return the material to its original state. For example, tearing a piece of paper.

Watch Out for These Misconceptions

Common Misconception

If you cannot see the change anymore, the material is back to its original state.

What to Teach Instead

Students sometimes think pressing a crumpled paper flat means it is fully restored. Close inspection shows remaining creases. Hands-on comparison of a never-crumpled sheet and a 'un-crumpled' one helps students see that the change left evidence.

Common Misconception

Cutting and tearing are the same type of change.

What to Teach Instead

Both remove parts of the material, but students often treat them identically. Using a magnifying lens to compare a cut edge (straight) and a torn edge (ragged) gives visual evidence that the processes are different, while both are still irreversible.

Common Misconception

Harder changes are always irreversible.

What to Teach Instead

Students may assume that if it takes effort, it cannot be undone. Bending thick cardboard requires effort but is still reversible. Sorting activities where students test their predictions directly correct this overgeneralization.

Active Learning Ideas

Sorting Activity: Can I Undo It?

Give each pair of students a set of identical paper strips. Students bend one strip, tear another, fold a third, and cut a fourth. They then attempt to reverse each change and sort them into two groups: 'easy to undo' and 'hard to undo'. Partners discuss their reasoning before sharing with the class.

25 min·Pairs

Gallery Walk: Before and After

Post six stations around the room, each showing an image of a material change (folded aluminum foil, torn fabric, snapped pretzel stick, crumpled paper, cut string, bent wire). Students walk with a clipboard and mark each as reversible or irreversible, then justify one choice in writing before a whole-class debrief.

30 min·Small Groups

Think-Pair-Share: The Impossible Fix

Hold up a torn piece of paper and ask: 'What would I need to make this look exactly like it did before?' Students think quietly, then discuss with a partner, then share ideas whole class. Guide students to notice that tape changes the paper further and the tear itself cannot simply be reversed.

15 min·Pairs

Collaborative Notebook: Change Journal

Small groups receive clay, paper, and a craft stick. They record what each material looks like before, then make three changes to each and sketch the results. The group labels each change as reversible or irreversible and compares notes with another group at the end.

35 min·Small Groups

Real-World Connections

• Tailors and seamstresses cut and sew fabric to create clothing, a process that involves irreversible changes to the material. They must carefully plan their cuts to achieve the desired garment shape.
• Origami artists create intricate sculptures by folding paper. These folds are reversible, allowing the paper to be unfolded and refolded into new designs, showcasing the malleability of the material.
• Recycling centers sort materials based on whether they can be easily remade into new products. Paper that is torn or heavily damaged might be harder to recycle than paper that is simply folded.

Assessment Ideas

Quick Check

Provide students with a strip of paper and scissors. Ask: 'First, carefully tear the paper in half. Now, try to put it back together exactly as it was. Can you do it? What word describes this kind of change?' Then, ask them to fold the paper in half and ask: 'Can you unfold this? What word describes this kind of change?'

Exit Ticket

Give each student a small card. On one side, they draw a picture of a material being bent or folded. On the other side, they draw a picture of a material being torn or cut. Below each drawing, they write one word: 'reversible' or 'irreversible'.

Discussion Prompt

Present students with a few common objects: a pipe cleaner, a rubber band, a piece of clay, and a dry leaf. Ask: 'Which of these materials can you bend or shape easily and then return to its original form? Which ones change in a way that is hard to undo? Why do you think that is?'

Frequently Asked Questions

What is the difference between a reversible and irreversible change for first graders?

A reversible change is one where the material can go back to how it started, like bending a pipe cleaner. An irreversible change cannot easily be undone, like tearing paper or breaking a cracker. For first graders, the key idea is whether the change 'sticks' or can be undone with no tools.

What materials work best for teaching reversible and irreversible changes in first grade?

Paper, clay, aluminum foil, pipe cleaners, and craft sticks are all excellent. Each can be bent, folded, or broken easily without safety concerns. Clay is especially useful because students can roll it flat, then roll it back into a ball, making reversibility very visible.

How does active learning help students understand reversible and irreversible changes?

When students physically manipulate materials and attempt to undo their own changes, the evidence becomes personal and memorable. Sorting real objects into 'undo' and 'cannot undo' categories creates a concrete framework that sticks better than a verbal explanation alone.

How does this topic connect to real-world experiences students have at home?

Students encounter reversible and irreversible changes constantly: unfolding a shirt (reversible), burning toast (irreversible), crumpling a drawing (reversible with effort), or breaking a toy (irreversible). Connecting classroom observations to these familiar events builds lasting conceptual understanding.