There’s nothing more aggravating as a Chemistry teacher than planning an awesome lab… and having the reaction flop.
You’ve spent time prepping materials, reviewing safety procedures, and building excitement. Students are ready. Goggles are on. You give the signal—and then… nothing. No color change. No bubbles. No reaction. Just 25 pairs of eyes staring at you, waiting for science to happen.
If you’ve been there, you know that feeling.
That’s exactly why I test my chemistry labs first.
It’s Not Just About Avoiding Failure
Testing a lab ahead of time isn’t about perfection—it’s about preparation.
Even when a lab “should” work on paper, classroom variables can change everything:
- Chemical concentrations may not be as expected
- Materials might be older or contaminated
- Timing might be off
- Instructions may not be as clear as you thought
Running the lab yourself helps you catch these issues before your students do.
Because once you’re in front of a class, troubleshooting in real time is a lot harder.
It Helps You See What Students Will Actually Experience
When you test a lab, you’re not just checking if it works—you’re stepping into your students’ shoes.
You start to notice things like:
- Where directions might be confusing
- Which steps take longer than expected
- Where students are likely to make mistakes
- What questions are going to come up
This allows you to refine your instructions and anticipate confusion before it derails the lesson.
You Can Adjust Before It Matters
Testing your chemistry labs gives you the chance to tweak things like measurements and quantities, timing and pacing, group setup, and safety considerations.
Sometimes it’s a small fix—like adjusting a concentration or rewriting a step. Other times, it’s realizing the lab needs a backup plan.
Either way, it’s much better to figure that out ahead of time than during class.
You Build Confidence (For You and Your Students)
True Story: in my eighth year teaching, I had ordered brand new test tube clamps for our ring stands that still had the rubber grips attached. I set up the lab the day before, putting a test tube in each clamp and attaching them to the ring stand, adjusting each one so that the test tubes were tight and positioned at an angle.
The day of the lab, students began heating the substance in the tubes with their alcohol burners when the rubber grips caught on fire.
Since I had conducted this specific lab dozens of times, I didn’t test it beforehand. Therefore, I wasn’t thinking about the rubber grips and how high the flames might reach. Students were looking at me waiting for answers while tiny flames started appearing around the room at nearly every lab station. At that moment, I had two choices: panic or turn it into a teachable moment.
My point is students can tell when something isn’t going as planned.
When you’ve tested your lab, you walk into the classroom with confidence. You know what should happen, what might go wrong, and how to respond.
That confidence matters. It keeps the lesson moving and helps maintain student trust—even if something unexpected happens.
And, trust me, no matter how many times you may have carried out a lab, there’s always that chance it doesn’t go quite as planned.
You Still Need a Backup Plan
You may not want to hear it, but even with testing, labs don’t always go perfectly.
That’s why I always prep the following:
- A related demo (so students can at least visualize the expected results)
- Photos or videos of how the lab should have gone
- A discussion plan if things go sideways
Testing doesn’t guarantee success—but it dramatically increases the odds.
It’s About Protecting the Learning Experience
At the end of the day, testing labs isn’t just about avoiding frustration—it’s about protecting student learning.
A successful lab creates engagement, curiosity, and deeper understanding. A failed lab without prep can lead to confusion and missed opportunities.
So, testing your labs first might feel like one more thing on your already full plate—but it’s one of the most impactful things you can do.
Taking a little extra time beforehand ensures that when your students walk into the lab, they’re set up for success—not disappointment.