Unit 7.1 Supplements
Pirl Experimental • OpenSciEd in my classroom
How I supplement and shorten OpenSciEd Unit 7.1
The chemistry ideas I keep, the resources I return to, and how I connect hands-on investigations to models of atoms and molecules.
I want students to leave a chemistry unit able to explain what happened. They should be able to describe the evidence they observed, model the particles involved, and account for the matter before and after a change. That understanding becomes especially useful when we move into chemical reactions in living things.
OpenSciEd Unit 7.1: Chemical Reactions & Matter gives students a compelling starting point: a bath bomb that fizzes and seems to disappear in water. The unit develops explanations through investigations, property data, and models. In my classroom, I have used that foundation in different ways, including a more compact chemistry mini-unit.
Three resources are especially useful in that work: the American Chemical Society’s Middle School Chemistry website, PhET Interactive Simulations, and the Identification of Chemical Reactions Kit sold by Carolina. I value all three whether I am working within OpenSciEd, adapting it into a shorter sequence, or teaching middle school chemistry through another approach.
The important part is deciding what each resource helps students figure out.
The chemistry I keep at the center
My chemistry materials have changed over time. An earlier mini-unit starts with bath bombs and includes dissolving, heating and cooling matter, and comparing the density of clear liquids. A later version puts more emphasis on building molecules, identifying evidence of chemical reactions, and explaining conservation of matter.
Across those versions, a few questions keep returning:
- What does matter look like at a scale we cannot see?
- How can properties help us distinguish substances?
- What evidence supports the claim that a chemical reaction occurred?
- How can new substances form while the atoms are conserved?
These questions help me decide what deserves time. Students need experiences that connect the visible event to a particle model. They also need opportunities to explain that connection themselves.
My shorter sequence sometimes introduces atoms and molecules earlier than the original OpenSciEd storyline does. That changes the learning progression. In the full unit, the need to distinguish atoms from molecules develops through students’ investigations. In my mini-unit, I may establish that distinction more directly so students can use it in the investigations that follow. When supplementing the full storyline, I would place those resources where they support the ideas students are developing.
How I use ACS Middle School Chemistry
ACS Middle School Chemistry is one of my favorite places to find a clear connection between an observable phenomenon and a molecular explanation. The site brings together investigations, animations, videos, student activity sheets, and teacher background information.
There are direct examples of this in my chemistry slides. For our work on heating and cooling matter, I link to ACS models of solids, liquids, and gases. Students draw each state under cooler and warmer conditions, then explain what changes in the motion and spacing of the particles.
The Chapter 1 simulations support that comparison. My slides also use the thermometer interactive: students draw a cold and a hot thermometer, include particles, and explain how the thermometer represents temperature.
The drawing and explanation give the animation a purpose. A student who writes “it gets hotter” still has work to do. The model should help the student explain what is happening to the particles and how that connects to the visible change.
ACS also gives me options when I need a different example or a more focused explanation. Chapter 6: Chemical Change includes resources on gas production, precipitates, energy changes, and pH. Those are useful places to look when planning a supplement to our reaction investigations.
I can select the animation, investigation, or reading that serves the question we are working on. That flexibility makes the site useful across different chemistry sequences.
How I use PhET: build it, draw it, account for it
My mini-unit includes activity sheets for three PhET simulations. Each one gives students a different way to work with the same core ideas.
Build a Molecule
With Build a Molecule, students practice connecting a molecule’s name, formula, structure, and atoms. My capture sheet asks them to build molecules, record their names and formulas, draw representations, and count the number and type of atoms.
The activity moves from single molecules to multiple molecules and then to the playground, where students choose additional molecules to build. That progression gives us a concrete way to discuss the difference between the atoms within one molecule and the total atoms represented by several molecules.
My slides remind students to put element letters inside their drawn atoms. Color helps, but the model also needs to communicate identity. I want students to be able to explain what each part represents.
Reactants, Products and Leftovers
Reactants, Products and Leftovers gives us an accessible entry into conservation. We begin with the sandwich model and ask what the ingredients, sandwiches, and leftovers represent. Students can explore different starting amounts and record what they produce and what remains.
Then we connect that reasoning to molecules. My activity sheet asks students to compare the number of atoms before and after the reaction, including atoms in leftover reactants. Counting only the finished products would leave part of the system unaccounted for.
The sandwich model is an analogy; making a sandwich is not itself a chemical reaction. Its usefulness is in helping students reason about combinations, proportions, and leftovers before applying those ideas to a chemical model.
Balancing Chemical Equations
With Balancing Chemical Equations, students connect equations to particle drawings and visual balance tools. My activity asks them to record a balanced equation, draw the molecules, and represent the balance. The game comes after that initial work.
Here, the equation gives students another way to account for atoms. Changing a coefficient changes the number of molecules represented; changing a subscript changes the substance. I want the numbers to mean something in their models.
Formal symbolic equation balancing is beyond the assessment boundary of MS-PS1-5. I use it as an added representation and practice opportunity. A student’s explanation and particle model remain essential evidence of understanding conservation.
How the Carolina kit supports our reaction-evidence lab
The Identification of Chemical Reactions Kit sold by Carolina is another useful resource. It is a Lab-Aids kit that uses Chemplates to investigate combinations of chemicals and observe changes such as gas production, precipitate formation, color changes, and heat release.
My reaction-evidence lesson uses a numbered combination chart. The capture sheet lists the 21 pairings among seven numbered substances, with space to describe evidence for each combination. That structure helps students keep track of what they mixed and connect each observation to a particular trial.
The kit fits this kind of comparative investigation well. Students have several opportunities to observe changes, record details, and compare results across combinations. The learning comes from those comparisons and the explanations students build from them.
The follow-up question matters: What evidence supports the claim that a new substance formed?
My progress trackers include questions such as whether bubbles always indicate a chemical reaction and whether a color change is enough to make that claim. Those questions help us examine the limits of an observation. Boiling produces bubbles, for example, while the substance remains water.
The “NR” shorthand on my capture sheet is also a useful discussion point. No visible evidence of a reaction is a more careful observation than claiming that no chemical change could possibly have occurred. Students should learn to describe what they can support with their evidence.
For anyone using the kit, the manufacturer’s procedures, protective equipment requirements, and disposal directions should guide the lab setup.
How I make the sequence shorter
The biggest change in my mini-unit is how I organize the experiences. I group the work around a small set of questions and use selected investigations and models to develop the answers.
This is a useful way to think about the choices reflected in my materials:
| Teaching focus | What I preserve | How I can adjust the time |
|---|---|---|
| Bath bombs and dissolving | A phenomenon students can observe, question, and explain | Use a focused investigation and return to its explanation as ideas develop. |
| Particle behavior and properties | Models and data that help distinguish substances and changes | Select ACS visuals and property investigations according to the background students need. |
| Evidence of reactions | Observations tied to specific chemical combinations | Use one organized comparison lab, then spend time interpreting the evidence. |
| Atoms, molecules, and conservation | Drawings and counts that account for every type of atom | Connect the PhET activities through a common modeling task and adjust the amount of practice. |
| Making sense of the learning | A main idea, a model, supporting details, and new questions | Reuse a consistent progress-tracker format throughout the sequence. |
This is a planning framework, not a fixed day-by-day calendar. My materials show different versions, and the amount of support students need affects the time each question deserves.
I also distinguish the essential chemistry from extensions. Some versions of my materials include temperature changes during reactions. That can provide a bridge into chemical reactions and energy, but it adds to the scope of the mini-unit. Naming that choice helps me decide whether it belongs in the time available.
The notebook is where the pieces come together
The simulations, animations, and labs all feed into students’ notebooks. My progress trackers ask for an answer to the lesson question, a labeled and captioned model, three brief key details, and at least two questions for what comes next.
That repeated structure gives students a familiar way to organize their thinking. It also gives me something more useful to examine than whether they finished an activity.
Can they connect an observation to a model? Can they distinguish an atom from a molecule? Does their reaction drawing conserve each type of atom? Can they explain why an observation supports their claim?
Because I teach students from Resource through Honors, those tasks also give me room to adjust support. I can provide a partially completed model, reduce the number of examples, or offer a sentence frame. I can also ask students to critique a model, account for leftovers, or explain why an observation alone is insufficient evidence. The chemistry question can stay consistent while the support and expected reasoning change.
ACS helps me connect observations to particle behavior. PhET gives students opportunities to manipulate, represent, and count particles. The reaction kit gives us physical evidence to examine. Together, they support the kind of chemistry instruction I want: students using observations and models to explain how substances change and where the matter goes.
