If you’re getting ready for the AP Biology exam, then you’re probably spending quite a bit of time studying cell structure. But keeping all the structures straight and understanding each one’s function can be confusing!

That’s why we’re breaking down cell structures for you, starting with the endoplasmic reticulum, or ER. In this article, we’ll teach you everything you need to know about the endoplasmic reticulum, including how it functions in a cell. We’ll even break down the differences between the rough endoplasmic reticulum and the smooth endoplasmic reticulum!

Ready? Then let’s get started!

On March 29, 1869, two soldiers and a young boy pushed a small boat into the icy waters of Newport Harbor.

The soldiers needed passage to the nearby Fort Adams and the boy told them he knew how to navigate the turbulent waters of the harbor quickly and safely. The trio hadn’t been at sea for very long when a snowstorm descended upon Rhode Island.

The waves became more and more choppy and soon, the boat overturned. The boy was quickly lost, succumbing to the freezing waters. The soldiers managed to grab hold of the upside down boat and clung to it, helplessly.

From the shore, a twelve-year-old girl saw the capsized boat and knew immediately what she needed to do. Running to her own boat without pausing to put on her coat or shoes, the girl rushed into the dangerous harbor and rowed towards the dying men.

That girl was Ida Lewis.

What is a perfect square? How do you know if a number is a perfect square?

In this article, we’ll define perfect squares, provide a list of the first 25 perfect squares (and the integers that make them up), and teach you how to tell if a number is a perfect square.

Knowing when where and how to best use a calculator on the ACT can be tricky. You are allowed to bring a calculator on test day (none will be provided for you), and it can mean the difference of several points on the ACT to have a calculator versus having none.

But what kind of calculator should you bring and how should you make best use of it during the test? In this guide, we’ll cover everything you need to know about calculators on the ACT, from when you're allowed to use them, to what kinds are allowed, to how to avoid the most common ACT calculator mistakes.

The hole punch was actually invented decades before it became a staple of modern offices. Read this guide to learn more about hole punch history, why the original inventor of the hole punch was contested, and how the hole punch has evolved over the centuries.

We’ve all stumbled on a web page that just doesn’t work. You know the type: the links aren’t clickable, the scrolling is all over the place, and sometimes...they automatically play music. (The worst.)

When a website misbehaves, bad JavaScript is usually at fault. That’s because JavaScript is the scripting language that controls the interactive elements of a website. In fact, JavaScript is actually a robust, powerful scripting language that automates processes like animating images or providing autofill suggestions. Basically, JavaScript is one of the fundamental coding languages of the web.

Like any language, there’s lots you can do with JavaScript. But today, we’re going talk about one specific type of JavaScript command: the TypeOf function. In this article, you’ll learn about the JavaScript TypeOf function, including what it is, how it works, and its most common uses.

So let’s dive in!

The Cartesian plane (or the x-y plane) is a two-line graph on which you plot ordered pairs. The two intersecting lines of the Cartesian plane make four distinct graph quadrants.

In this article, we’ll discuss what graph quadrants are, how to manipulate data points on graph quadrants, and walk through some sample graph quadrant problems.

Whether you've already graduated or are about to graduate from college, if you're asking yourself, "Should I get a master’s degree?" it’s time to dig deep and find the answer. A master's degree can be useful for particular careers—but it's also expensive and time-consuming. So is a master’s degree right for you?

In this guide, we go over what a master's degree is, four key questions to ask yourself before you decide to get one, the pros and cons of getting one, and three tips to help you decide on the best master’s degree program for you.

Have you heard about contour line art but aren’t sure what it is? The good news is that you’ve likely already made dozens, maybe even hundreds, of contour line drawings throughout your life without realizing it! Contour drawing is one of the easiest and most effective ways to improve your hand-eye coordination and drawing skills.

In this guide, we explain what contour lines in art are and how you make contour line art. We also suggest different contour drawing exercises so you can keep improving your skills.

If you’re taking a geometry or trigonometry class, one of the topics you’ll study are trigonometric identities. There are numerous trig identities, some of which are key for you to know, and others that you’ll use rarely or never. This guide explains the trig identities you should have memorized as well as others you should be aware of. We also explain what trig identities are and how you can verify trig identities.

In math, an "identity" is an equation that is always true, every single time. Trig identities are trigonometry equations that are always true, and they’re often used to solve trigonometry and geometry problems and understand various mathematical properties. Knowing key trig identities helps you remember and understand important mathematical principles and solve numerous math problems.

As you prepare for the AP Literature exam, one of the things you’ll have to do is become an expert in a few literary works that you can use on the composition portion of the exam. We recommend that you choose four to five notable works with different genres and themes to make sure you can write an amazing student choice essay.

(Actually...practicing analyzing literature will help you on the whole exam, not just the written portion, so it’s a win-win situation!)

But just because these works have to be “notable” with “literary merit” doesn’t mean they need to be boring, too! That’s why we’re talking about Edgar Allan Poe’s short story, “The Cask of Amontillado,” as a good choice for your AP exam. Not only is it widely recognized as an excellent piece of literature, it’s got a little of everything: horror! Suspense! A surprise twist! And as an added bonus...it’s short.

To bring you up to speed, we’ll start with “The Cask of Amontillado” summary, then we’ll jump into character and thematic analyses. By the time you finish this article, you’ll be able to write fearlessly about “The Cask of Amontillado” on your AP exam.

Adding and subtracting fractions can look intimidating at first glance. Not only are you working with fractions, which are notoriously confusing, but suddenly you have to contend with converting numerators and denominators, too.

But adding and subtracting fractions is a useful skill. Once you know the vocabulary and the basics, you’ll be adding and subtracting fractions with ease. This guide will walk you through everything you need to know for adding and subtracting fractions, including some example problems to test your skills.

All living things are made of cells and all cells have different parts that perform specific functions. One of the parts present in every cell is called the cell membrane.

In this article, we’ll discuss the cell membrane structure and function, answering the questions “what does the cell membrane do?” and “why is the cell membrane important?”

If you’re planning to take the SAT, you may have heard of this strange question type known as grid-ins. You probably know that there are multiple-choice questions and an optional essay, but what are grid-ins? Problems that require you to draw pictures or graphs, perhaps? The reality is grid-ins are almost identical to multiple-choice questions; they just don’t provide answer choices.

This guide will explain what grid-ins are, discuss where they appear, outline how many appear on the SAT, and provide tips on answering them. 

In 2018, Scientific American published an article titled “The Number of Americans with No Religious Affiliation Is Rising,” which looked at the rising number of Americans who don’t identify with any religion. In 2018, a survey done by the Pew Research Center found 34 to 36 percent of millennials identify as atheist, agnostic, or just “nothing in particular.”

While most people have a general understanding of atheism, agnosticism can be a little more confusing since it falls in the grey area between total belief and total disbelief in the existence of a higher power and/or God.

In this article, we’ll explore what it means to be agnostic. First, we’ll define the term agnostic and talk about what agnosticism looks like in practice, then we’ll dive into the differences between being agnostic vs. atheist. Finally, we’ll share a list of famous people who are agnostics.

So let’s get started!