150 Essential Science Expressions to Boost ESL Conversations

If you’re an ESL teacher looking to boost your students’ confidence and skills in talking about science, this post is just what you need. Here, you’ll find the ultimate list of science expressions organized into 15 clear categories. These expressions are perfect for helping learners build their vocabulary and speak naturally about scientific topics.

This resource goes beyond just words. It offers useful phrases for conversations, asking g and answering questions, and explaining scientific ideas clearly. You can easily design fun classroom activities like role-plays and debates to make learning interactive and engaging. Plus, you’ll find common idioms and expressions that make science talk more lively and interesting.

With this list, your students will be ready to handle different science topics confidently. Whether they are describing experiments, making predictions, or discussing environmental issues, they will have the right words and phrases at their fingertips. Using these expressions in lessons will help your students communicate more naturally and improve their speaking skills faster.

Don’t waste time searching for scattered materials. This post gathers everything you need in one place, saving you preparation time and giving your lessons a clear focus. If you want to make science classes fun, practical, and easy to follow, keep reading — this is the best ESL teaching resource for science conversations you’ll find anywhere.

Why Talking About Science Is Important in ESL Classes

Science is a big part of our daily lives. We hear about it on the news, in school, and even when we use technology. For ESL learners, knowing how to talk about science helps them understand the world better.

When students learn science expressions, they can join conversations about important topics like the environment, health, and technology. This makes their English more useful and interesting.

Science also teaches students how to ask questions, explain ideas, and think carefully. These skills are helpful not just in science but in everyday communication too.

Many students need to study science in English for school or work. Being confident with science vocabulary and phrases helps them do better in these situations.

Finally, talking about science in ESL classes makes lessons more exciting. It gives students real reasons to practice speaking, listening, and thinking in English.

1. Describing Scientific Processes

When talking about science, learners often need to explain how things happen step-by-step. These expressions help students describe scientific processes clearly and simply, whether it’s a natural event or a lab experiment.

Common Expression	Situation
First, the water evaporates.	Describing the beginning of a process, like water turning into vapor.
Then, it condenses into clouds.	Explaining the next step where vapor turns back into liquid.
After that, the rain falls to the ground.	Talking about what happens following condensation.
The cells divide and multiply.	Describing a biological process happening inside living things.
Heat causes the ice to melt.	Explaining a process triggered by temperature changes.
The mixture changes color.	Noticing a visible change during a chemical reaction.
The plant absorbs sunlight for energy.	Explaining how plants use light in photosynthesis.
Air pressure pushes the liquid up.	Describing physical forces in a process.
The gas expands when heated.	Talking about how gases behave under heat.
The enzyme breaks down the food.	Explaining how enzymes help in digestion or other reactions.

2. Making Hypotheses and Predictions

These expressions help learners guess or predict what might happen in a scientific context. They are useful for encouraging students to think critically and talk about possible outcomes.

Common Expression	Situation
I think the plant will grow faster with more sunlight.	Predicting growth based on a condition.
It might rain tomorrow.	Expressing uncertainty about weather.
If we increase the temperature, the reaction will speed up.	Making a conditional prediction in an experiment.
I guess the solution will change color.	Speculating about what will happen next.
The experiment could take longer than expected.	Predicting the duration of a process.
It’s likely that the metal will rust over time.	Stating a probable outcome based on evidence.
We expect the seeds to sprout in three days.	Talking about anticipated results.
Maybe the bacteria will die without food.	Suggesting a possible effect of a condition.
I predict the liquid will evaporate quickly.	Making a clear prediction about evaporation.
The data suggests the temperature affects growth.	Inferring based on preliminary results.

3. Asking and Answering Scientific Questions

These expressions help learners form questions to explore scientific ideas and provide clear answers. They’re great for encouraging curiosity and discussion in the classroom.

Common Expression	Situation
What causes the seasons to change?	Asking about natural phenomena.
How does photosynthesis work?	Inquiring about a biological process.
Why does ice melt when heated?	Questioning a physical change.
When does a chemical reaction happen?	Asking about timing of reactions.
Where can we find this element?	Asking about location or source.
Who discovered this theory?	Asking about a scientist or inventor.
Can plants grow without sunlight?	Checking for possibilities or exceptions.
Is this experiment safe to do at home?	Asking about safety precautions.
What are the effects of pollution?	Inquiring about environmental impact.
How long does it take for water to boil?	Asking about duration of a process.

4. Expressing Cause and Effect

These expressions help learners explain why something happens and what results from it. They are key for describing scientific relationships clearly.

Common Expression	Situation
Because of the high temperature, the ice melted quickly.	Explaining the cause of melting.
The experiment failed due to contamination.	Stating the reason for failure.
As a result, the solution changed color.	Showing what happened next.
Since the plant didn’t get sunlight, it grew slowly.	Linking lack of sunlight to slow growth.
The reaction happened because we added heat.	Explaining what caused the reaction.
The water boiled, so the gas escaped.	Describing an effect of boiling.
Due to pollution, many fish died.	Explaining environmental damage.
The magnet attracts iron because of magnetic force.	Stating the cause of attraction.
The temperature dropped, causing the water to freeze.	Explaining freezing as a result.
Because the enzyme was missing, the food wasn’t digested.	Explaining failure in digestion.

5. Comparing and Contrasting

These expressions help learners talk about similarities and differences between scientific objects, processes, or ideas. They make discussions clearer and more precise.

Common Expression	Situation
This chemical is stronger than the other one.	Comparing strength of chemicals.
Unlike plants, animals cannot make their own food.	Showing a difference between plants and animals.
Both metals conduct electricity well.	Pointing out a similarity between metals.
The new model is faster but less accurate.	Comparing advantages and disadvantages.
Water boils at 100°C, whereas alcohol boils at a lower temperature.	Contrasting boiling points.
The first experiment used salt, while the second used sugar.	Comparing different experiment setups.
Similar to the sun, stars give off heat and light.	Showing similarities in natural objects.
The two solutions look alike but react differently.	Noting visual similarity with different reactions.
Carbon dioxide is heavier than oxygen.	Comparing the weight of gases.
Both methods work, but one is more cost-effective.	Comparing effectiveness and cost.

6. Describing Experiments

These expressions help learners explain what happens during an experiment clearly and simply. They’re perfect for talking about procedures and observations.

Common Expression	Situation
We mixed the two liquids and observed the reaction.	Explaining the steps of an experiment.
The solution turned blue after adding the indicator.	Describing a change during the experiment.
We heated the mixture for ten minutes.	Talking about the experiment’s conditions.
The test tube cracked when it got too hot.	Reporting an unexpected result.
We recorded the temperature every five minutes.	Explaining data collection.
The experiment showed that plants need sunlight to grow.	Summarizing the result.
We repeated the experiment to check the results.	Explaining the importance of repetition.
The gas produced was collected in a balloon.	Describing how they captured a product.
After mixing, the solution became cloudy.	Noticing a visible change.
We used a control group to compare results.	Explaining the experimental setup.

7. Expressing Agreement and Disagreement

These expressions help learners share their opinions during scientific discussions, whether they agree or disagree politely and clearly.

Common Expression	Situation
I agree with your theory because the data supports it.	Showing agreement based on evidence.
That’s a good point, but I think there’s another explanation.	Agreeing partly while suggesting a different view.
I’m not sure I agree with that conclusion.	Politely disagreeing or expressing doubt.
Actually, the results show something different.	Pointing out a conflicting fact.
I see what you mean, but consider this fact.	Acknowledging a view while offering a counterpoint.
Yes, that makes sense to me.	Simple agreement.
I don’t think that’s correct because…	Explaining why you disagree.
Your data seems interesting, but more research is needed.	Agreeing partially while asking for caution.
I support your idea because it fits with previous studies.	Expressing strong agreement.
I respectfully disagree with that hypothesis.	Polite disagreement.

8. Giving Instructions

These expressions help learners clearly explain steps and commands during science activities or experiments. They are useful for guiding classmates or describing procedures.

Common Expression	Situation
Add two drops of the solution to the test tube.	Giving a specific instruction in an experiment.
Stir the mixture slowly for five minutes.	Explaining how to mix ingredients.
Measure 100 milliliters of water.	Instructing on the amount to use.
Heat the beaker over the flame carefully.	Giving a safety-related instruction.
Record your observations in the notebook.	Telling students to write down what they see.
Use the microscope to look at the cells.	Directing how to use equipment.
Shake the bottle before opening it.	Giving preparation instructions.
Place the sample under the light source.	Telling where to position materials.
Don’t touch the chemicals with bare hands.	Warning about safety precautions.
Turn off the equipment after use.	Giving instructions on finishing the task.

9. Describing Materials and Equipment

These expressions help learners talk about the tools and materials they use in science. Knowing how to describe equipment makes instructions and explanations clearer.

Common Expression	Situation
We used a microscope to see the tiny cells.	Talking about using equipment to observe small things.
The beaker is made of glass.	Describing the material of a container.
This test tube holds about 50 milliliters of liquid.	Describing the capacity of equipment.
The thermometer measures temperature.	Explaining the function of a tool.
The petri dish contains bacteria cultures.	Talking about the container for growing samples.
This scale weighs small amounts precisely.	Describing the purpose of equipment.
The pipette helps us add small drops.	Explaining the use of a tool.
We wore safety goggles to protect our eyes.	Talking about safety equipment.
The Bunsen burner produces a flame for heating.	Describing a heating tool.
The plastic gloves prevent contamination.	Explaining the use of protective materials.

10. Explaining Measurements and Data

These expressions help learners talk about numbers, quantities, and results clearly, which is essential for sharing scientific information.

Common Expression	Situation
The temperature rose to 100 degrees Celsius.	Describing a change in temperature.
We measured 50 milliliters of water.	Talking about quantity.
The sample weighed 10 grams.	Reporting weight.
The data shows a steady increase.	Explaining trends in results.
The average was calculated from five trials.	Talking about how data was processed.
There was a significant difference between groups.	Describing important statistical results.
The results were recorded in a table.	Explaining where data is kept.
The graph shows a sharp decline.	Describing visual data.
The concentration was higher in the second solution.	Talking about levels of substances.
We compared the measurements from different samples.	Discussing comparisons in data.

1. Expressing Uncertainty and Doubt

These expressions help learners say when they are unsure or when something is only a possibility in science.

Common Expression	Situation
It might be caused by an unknown factor.	Expressing a possible cause without certainty.
I’m not sure if this is correct.	Showing doubt about information.
It could happen under certain conditions.	Suggesting a possibility.
There’s a chance the results are wrong.	Expressing uncertainty about data.
Maybe this is just a coincidence.	Speculating without confidence.
I don’t think we have enough evidence yet.	Saying more proof is needed.
It’s possible but unlikely.	Expressing low probability.
The theory hasn’t been proven yet.	Indicating something is not confirmed.
We can’t be certain about the outcome.	Admitting uncertainty.
It’s just a hypothesis for now.	Saying an idea is tentative.

12. Expressing Opinions and Ideas

These phrases help learners share their thoughts, beliefs, or interpretations in scientific discussions.

Common Expression	Situation
In my opinion, this method is more effective.	Sharing a personal belief.
I think this experiment was successful.	Expressing a positive judgment.
From my point of view, the data is reliable.	Giving a perspective on data.
I believe this theory explains the results.	Stating a belief about a theory.
It seems to me that the sample was contaminated.	Offering a reasoned guess.
I feel this approach could be improved.	Suggesting possible improvement.
My idea is to test it again with more samples.	Proposing an action.
I guess this could work in different conditions.	Speculating about possibilities.
To me, the evidence supports this conclusion.	Expressing agreement with data.
I would suggest trying a different technique.	Making a polite recommendation.

13. Describing Natural Phenomena

These expressions help learners talk about events and features in nature, such as weather, animals, and planets.

Common Expression	Situation
The volcano erupted and released lava.	Describing volcanic activity.
It rained heavily last night.	Talking about weather events.
The sun rises in the east.	Stating a natural fact.
The animal migrated to a warmer area.	Describing animal movement.
The earthquake caused a lot of damage.	Talking about a natural disaster.
The river flows into the ocean.	Describing water movement.
The moon orbits the Earth every 27 days.	Talking about planetary motion.
The leaves change color in autumn.	Describing seasonal changes.
The storm brought strong winds and hail.	Talking about severe weather.
The forest provides habitat for many species.	Describing ecological facts.

14. Discussing Environmental Issues

These expressions help learners talk about pollution, conservation, and climate change clearly and responsibly.

Common Expression	Situation
We need to reduce plastic waste to protect the ocean.	Talking about pollution prevention.
Climate change is causing sea levels to rise.	Explaining environmental impact.
Recycling helps conserve natural resources.	Describing positive actions.
Air pollution affects human health.	Talking about pollution effects.
Protecting endangered species is important.	Discussing conservation efforts.
We should use renewable energy sources.	Suggesting sustainable alternatives.
Deforestation leads to loss of wildlife habitat.	Explaining negative environmental effects.
The government passed new laws on emissions.	Talking about environmental policies.
People must reduce their carbon footprint.	Encouraging responsible behavior.
Cleaning up rivers improves water quality.	Describing environmental restoration.

15. Expressing Scientific Results and Conclusions

These phrases help learners summarize their findings and explain what their experiments showed.

Common Expression	Situation
The experiment showed that plants grow better with fertilizer.	Summarizing a positive result.
Our data suggests that the hypothesis is correct.	Indicating support for a theory.
The results indicate a strong correlation between variables.	Explaining relationships found.
We concluded that temperature affects reaction speed.	Stating a conclusion.
The study demonstrated significant changes in behavior.	Reporting important findings.
The evidence supports our original assumption.	Confirming a prediction.
The analysis revealed unexpected outcomes.	Noting surprising results.
Based on the data, we reject the null hypothesis.	Reporting statistical conclusion.
The findings are consistent with previous research.	Comparing with earlier studies.
Our research contributes new insights to the field.	Explaining the value of the study.

Conclusion

Using science expressions in ESL classes opens many doors for learners. It helps students speak clearly about important topics and feel confident joining real-world conversations. This resource gives you everything you need to teach these expressions in fun and meaningful ways.

With this list, your lessons will be more engaging and your students will improve faster. Start using these phrases today to make science talk easier and more natural for your learners!

FAQs about Using Science Expressions in ESL Classes

Why should I teach science expressions to ESL students?
Teaching science expressions helps students build practical vocabulary and improve their ability to talk about important topics like environment, health, and technology.

How can I use these expressions in classroom activities?
You can create role-plays, debates, and question-answer sessions using the expressions to make lessons interactive and help students practice real conversations.

Are these expressions suitable for all levels of ESL learners?
Yes! The expressions are simple and clear, making them easy to adapt for beginners as well as more advanced students.

Can science expressions improve other English skills?
Absolutely. Learning to express scientific ideas helps improve speaking, listening, reading, and writing skills because students practice clear communication and critical thinking.

How do I encourage shy students to use science vocabulary?
Start with group work or pair activities where students feel more comfortable, then gradually encourage sharing in larger groups or presentations.

Is it important to teach idioms and informal phrases related to science?
Yes, idioms and informal phrases make language more natural and help students understand everyday conversations better.

Can these expressions be used outside the classroom?
Definitely. They prepare students for conversations in school, work, and social settings where science topics may come up.

How often should I review and practice science expressions?
Regular practice is key. Incorporate these expressions into daily lessons and review them frequently to help students remember and use them confidently.

What if students make mistakes using science expressions?
Mistakes are part of learning. Encourage students to keep trying and gently correct them to build their confidence over time.

Where can I find more resources to teach science in ESL?
You can explore websites, textbooks, and teaching communities online. This post is a great starting point, and you can also create your own materials based on these expressions.