Same Pieces, New Thing
A 50-minute Grade 2 lesson on showing that an object made of a small set of pieces can be taken apart and rebuilt as something new.
Same Pieces, New Thing is a free 50-minute Grade 2 science lesson plan for Common Core standard 2-PS1-3 — show that a set of pieces can be taken apart and built into something new. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.
- Grade:
- Grade 2
- Length:
- 50 minutes
- Standard:
- 2-PS1-3
Grade 2 · Physical Science
2-PS1-3
Make observations to construct an evidence-based account of how an object made of a small set of pieces can be disassembled and made into a new object.
Objective
Students will be able to rebuild one set of pieces into a different object and account for every piece.
Students are successful when they can
- Builds, dismantles and rebuilds using the same pieces.
- Counts the pieces before and after.
- Says what changed and what did not.
What you need
- A set of twelve identical blocks per group
- A counting mat so no piece goes missing
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up — count them first
5 min- Count twelve blocks onto the mat in front of the class.
- Ask why counting first might matter later.
Teach — three things, twelve blocks
13 min- Build a tower twelve high. Count it.
- Take it apart and count back to twelve.
- Build a wall six long and two high. Count it.
- Take it apart and build a bridge. Count again.
- Ask what changed each time: the shape and what it can do.
- Ask what never changed: the twelve blocks themselves.
“Same twelve. What changed, and what did not?”
Investigate — three builds each
17 min- Groups build, dismantle and rebuild three different objects from one set.
- They count the pieces after every dismantle.
- They draw all three builds side by side.
- They write one sentence saying what stayed the same throughout.
Independent practice
12 min- Students complete the 'Same Pieces, New Thing' page.
- Check the ordering shows dismantling between builds.
Close
3 min- Ask for something at home made of pieces that could be rebuilt.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Adds a piece to make the new build work.
Why: The design needed one more.
Fix: Count. If it is thirteen, it is a different set and the point is lost.
Thinks the blocks changed into something else.
Why: The object is new.
Fix: Count them and look at them. The blocks are identical; the arrangement changed.
Draws the builds without dismantling in between.
Why: Dismantling feels like undoing work.
Fix: Dismantling is the step the standard names. Show it in the sequence.
If they are not there yet
- Six blocks and two builds.
- A drawn outline of the first build to copy.
If they finish early
- Build three objects that each use every block.
- Say which build was strongest and why.
- Find a build the twelve blocks cannot make.
Exit ticket
One set of twelve blocks made a tower, then a wall, then a bridge. What changed and what stayed the same?
What to look for: The shape and its job changed; the same twelve blocks stayed the same. A claim that the blocks changed means the counting point needs another run.
Printable practice for 2-PS1-3
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- Same Pieces, New ThingNumber the steps from 1 to 4.
Questions about Same Pieces, New Thing
How long does the Same Pieces, New Thing lesson take?
50 minutes, split across 5 timed sections: warm-up 5 min, teach 13 min, investigate 17 min, independent practice 12 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.
Which standard does Same Pieces, New Thing teach?
2-PS1-3 — 2-PS1-3, Physical Science for Grade 2: “Make observations to construct an evidence-based account of how an object made of a small set of pieces can be disassembled and made into a new object.” In plain terms, show that a set of pieces can be taken apart and built into something new.
What do I need to teach this lesson?
A set of twelve identical blocks per group, a counting mat so no piece goes missing and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.
What mistakes should I expect in this lesson?
Three, each a reasoning error rather than carelessness: adds a piece to make the new build work; thinks the blocks changed into something else and draws the builds without dismantling in between. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.
How do I know whether the lesson worked?
The exit ticket asks: “One set of twelve blocks made a tower, then a wall, then a bridge. What changed and what stayed the same?.” The shape and its job changed; the same twelve blocks stayed the same. A claim that the blocks changed means the counting point needs another run. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.
Is there a worksheet to go with Same Pieces, New Thing?
Yes — 1 printable 2-PS1-3 worksheet, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.
Is Same Pieces, New Thing free to use?
Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 8 September 2026. Please do not resell it or republish it as your own.
Last reviewed 2026-09-08. Aligned to 2-PS1-3 of the Next Generation Science Standards.