Subjects
Triangle Congruence and Similarity Theorems
Triangle Properties and Classification
Linear Equations and Graphs
Geometric Angle Relationships
Trigonometric Functions and Identities
Equation Solving Techniques
Circle Geometry Fundamentals
Division Operations and Methods
Basic Differentiation Rules
Exponent and Logarithm Properties
Show all topics
Human Organ Systems
Reproductive Cell Cycles
Biological Sciences Subdisciplines
Cellular Energy Metabolism
Autotrophic Energy Processes
Inheritance Patterns and Principles
Biomolecular Structure and Organization
Cell Cycle and Division Mechanics
Cellular Organization and Development
Biological Structural Organization
Show all topics
Chemical Sciences and Applications
Atomic Structure and Composition
Molecular Electron Structure Representation
Atomic Electron Behavior
Matter Properties and Water
Mole Concept and Calculations
Gas Laws and Behavior
Periodic Table Organization
Chemical Thermodynamics Fundamentals
Chemical Bond Types and Properties
Show all topics
European Renaissance and Enlightenment
European Cultural Movements 800-1920
American Revolution Era 1763-1797
American Civil War 1861-1865
Global Imperial Systems
Mongol and Chinese Dynasties
U.S. Presidents and World Leaders
Historical Sources and Documentation
World Wars Era and Impact
World Religious Systems
Show all topics
Classic and Contemporary Novels
Literary Character Analysis
Rhetorical Theory and Practice
Classic Literary Narratives
Reading Analysis and Interpretation
Narrative Structure and Techniques
English Language Components
Influential English-Language Authors
Basic Sentence Structure
Narrative Voice and Perspective
Show all topics
101
β’
Jan 12, 2026
β’
Science wouldn't work without precise measurements. In this guide, we'll... Show more
Ever wondered how scientists make such exact measurements? They use the metric system (also called S.I. or System International Units) because it's more precise, easier to convert between units, and used worldwide. The metric system measures properties like time, mass, volume, and length.
The metric system has two key parts: prefixes that show the scale of measurement and suffixes that show what's being measured . Basic units include meters for length, grams for mass, and liters for volume. Each can be scaled larger or smaller using prefixes.
Understanding the prefix scale makes conversions simple. Moving up the scale (from smaller to larger units), you divide by 10, 100, or 1000. Moving down the scale (from larger to smaller units), you multiply. For example, 1 kilometer equals 1,000 meters, and 1 millimeter equals 0.001 meters.
Pro Tip: Remember this shortcut for the metric prefix order: "King Henry Died By Drinking Chocolate Milk" for Kilo-, Hecto-, Deka-, Base unit, Deci-, Centi-, Milli-
Converting between units is straightforward math. To convert 7 kilometers to meters: 7 km Γ = 7,000 m. The kilometers cancel out, leaving you with meters. Similarly, 23.7 mg Γ = 0.237 dg. With practice, you'll be able to do these conversions quickly!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help β all at your fingertips.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think itβs very much worth it and youβll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still donβt get it!!! In the end I think itβs worth it ππ β οΈAlso DID I MENTION ITS FREEE YOU DONβT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYβοΈβοΈβ οΈ
Thomas R
iOS user
Knowunity is the BEST app Iβve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the helpπ€π€
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.ππ©·π
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as Iβve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think itβs very much worth it and youβll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still donβt get it!!! In the end I think itβs worth it ππ β οΈAlso DID I MENTION ITS FREEE YOU DONβT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYβοΈβοΈβ οΈ
Thomas R
iOS user
Knowunity is the BEST app Iβve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the helpπ€π€
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.ππ©·π
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as Iβve seen! Geometry too!
Paul T
iOS user
Science wouldn't work without precise measurements. In this guide, we'll explore how scientists measure various properties like mass, volume, and length using the metric system. You'll learn how to convert between different units and why the metric system is the... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered how scientists make such exact measurements? They use the metric system (also called S.I. or System International Units) because it's more precise, easier to convert between units, and used worldwide. The metric system measures properties like time, mass, volume, and length.
The metric system has two key parts: prefixes that show the scale of measurement and suffixes that show what's being measured . Basic units include meters for length, grams for mass, and liters for volume. Each can be scaled larger or smaller using prefixes.
Understanding the prefix scale makes conversions simple. Moving up the scale (from smaller to larger units), you divide by 10, 100, or 1000. Moving down the scale (from larger to smaller units), you multiply. For example, 1 kilometer equals 1,000 meters, and 1 millimeter equals 0.001 meters.
Pro Tip: Remember this shortcut for the metric prefix order: "King Henry Died By Drinking Chocolate Milk" for Kilo-, Hecto-, Deka-, Base unit, Deci-, Centi-, Milli-
Converting between units is straightforward math. To convert 7 kilometers to meters: 7 km Γ = 7,000 m. The kilometers cancel out, leaving you with meters. Similarly, 23.7 mg Γ = 0.237 dg. With practice, you'll be able to do these conversions quickly!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help β all at your fingertips.
2
Smart Tools NEW
Transform this note into: β 50+ Practice Questions β Interactive Flashcards β Full Mock Exam β Essay Outlines
Explore key concepts of reaction rates, including collision theory, factors affecting reaction speed, and the role of catalysts. This summary covers essential exam questions and explanations related to reaction kinetics, temperature effects, and chemical equilibrium. Ideal for students preparing for chemistry assessments.
ChemistryExplore the key concepts of reaction rates, including concentration effects, collision theory, and factors influencing reaction speed. This summary covers essential principles such as the role of catalysts and the relationship between concentration and reaction rate, providing a clear overview for students studying kinetics. Ideal for exam preparation and quick reference.
ChemistryLearn about Ernest Rutherford's groundbreaking experiment that confirmed the presence of positive and negative charges within atoms and led to the discovery of the atomic nucleus.
ChemistryCalculate percent error and density
ChemistryExplore the concept of isotopes in chemistry, focusing on atomic number, mass number, and the differences in neutron count. This summary provides a clear definition and examples to enhance your understanding of isotopes and their significance in the study of elements.
ChemistryThis note contains the summary of the topics redox reaction, electrochemistry, nuclear chemistry, and stoichiometry.
AP ChemistryApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think itβs very much worth it and youβll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still donβt get it!!! In the end I think itβs worth it ππ β οΈAlso DID I MENTION ITS FREEE YOU DONβT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYβοΈβοΈβ οΈ
Thomas R
iOS user
Knowunity is the BEST app Iβve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the helpπ€π€
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.ππ©·π
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as Iβve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think itβs very much worth it and youβll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still donβt get it!!! In the end I think itβs worth it ππ β οΈAlso DID I MENTION ITS FREEE YOU DONβT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYβοΈβοΈβ οΈ
Thomas R
iOS user
Knowunity is the BEST app Iβve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the helpπ€π€
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.ππ©·π
Marco B
iOS user
homepage/newPositiveReviewText6
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as Iβve seen! Geometry too!
Paul T
iOS user
Algebra