These nouns describe how scientists work. Research is careful study (usually uncountable, so no "a research"), an experiment is one scientific test you can count, and a discovery is the new thing you find out.
Finding things out
research /rɪˈsɜːrtʃ/ — Mei conducted research on clean energy for the city.
experiment /ɪkˈsperɪmənt/ — Hiroshi repeated the experiment to check the results.
discovery /dɪˈskʌvəri/ — Amina described a major scientific discovery in her presentation.
Not ""Mei did a research on clean energy."" — say ""Mei did some research on clean energy."". Research is uncountable. Use some research or a piece of research, never a research.
Try it: Yasmin tested the same idea twice under the same conditions to see if she got the same result. She carried out an ___. (experiment / invention / research) Answer: experiment — An experiment is a single, countable scientific test, which is exactly what "twice under the same conditions" describes. An invention is a new device you create, not a test; and "a research" is wrong because research is uncountable and means the study as a whole, not one trial.
New things and better ways
An invention is a new physical thing or method someone creates. Innovation is a new idea or method that improves how something is done. Technology is the tools, machines and systems used to do work.
invention /ɪnˈvenʃn/ — The class discussed an invention that changed transportation.
innovation /ˌɪnəˈveɪʃn/ — The new booking system was an important innovation for the clinic.
technology /tekˈnɑlədʒi/ — The hospital invested in modern medical technology.
Not ""The wheel is an innovation."" — say ""The wheel is an invention."". An invention is a brand-new thing; an innovation is a fresh improvement to how something already works.
Try it: The school did not build anything new. It just found a smarter way to run its online lessons. That clever improvement was a real ___. (innovation / discovery / experiment) Answer: innovation — Innovation fits because it is a new method that improves something that already exists, which is running lessons better. A discovery is finding out something unknown, and an experiment is a test; neither matches "a smarter way to do what they already did."
Verbs: discover, invent, produce
These verbs are easy to mix up. Discover = find something that already existed but was not known. Invent = create something brand new. Produce = make or cause a result, especially in science or industry.
discover /dɪˈskʌvər/ — Researchers discovered new evidence about the illness.
invent /ɪnˈvent/ — Wei wants to invent a tool for organizing classroom cables.
produce /prəˈduːs/ — The experiment produced surprising results.
Not ""Marie Curie discovered a new machine."" — say ""Marie Curie discovered a new element."". You discover something that already exists in nature; you invent a machine or device that never existed before.
Try it: Diego built a completely new device to keep cables tidy, and nothing like it had existed before. He ___ it. (invented / discovered / researched) Answer: invented — Invent is right because the device is brand new and created by Diego. Discover would mean he found something that already existed, which contradicts "nothing like it had existed before"; and researched means he studied it, not that he built it.
People and big moments
A scientist is the person who studies the natural world and runs the experiments. A breakthrough is a sudden, important result that changes what people are able to do.
scientist /ˈsaɪəntɪst/ — The scientist repeated the test three times.
breakthrough /ˈbreɪkθruː/ — The new battery was a real breakthrough.
Try it: After years of slow progress, the team suddenly solved the problem, and the news called it a major ___. (breakthrough / experiment / technology) Answer: breakthrough — A breakthrough is a sudden result that changes what is possible. An experiment is one test along the way, and technology is the tools in general, so neither one names the moment of success.