The Tilt-A-Whirl Can Help Explain Normative Data

Imagine you and your niece are spending the day at a nearby amusement park. While spinning rides are not your favorite, she can’t wait to get on the Tilt-A-Whirl. You agree that she can ride it on her own, and she diligently waits in the long line, while you stand outside the gate with your camera primed and ready. Eventually, she reaches the front, but before she can board, she must stand against the measuring stick mounted to the wall: “MUST BE THIS TALL TO RIDE ALONE”. Even when pressing her heels back firmly and standing as tall as possible, she still falls short of the 46-inch minimum height requirement. 

“Sorry, you can’t ride alone,” the operator states. You dart over in protest, “But wait, I can show you her height on a growth chart; she’s in the 75th percentile!” He looks back at you with confusion because, of course, being in the 75th percentile on a growth chart does not mean she has met the ride’s minimum height requirement. Unfortunately, it looks like you’ll be boarding the Tilt-A-Whirl along with her.

Norms and Standards Are Different

Yes, we know this story is fiction and we don’t actually believe anyone is pulling out growth charts to argue about amusement rides, but it does demonstrate the important difference between using norms and standards to interpret data.

• Norms represent what is typical and are usually stated as percentiles; in this story, the norms on the growth chart represent the typical growth paths for children of a specific age. Being in the 75th percentile for height isn’t good or bad, it simply means that compared to others, your niece is taller than 75% of other children her age. 

• Standards, on the other hand, define what is expected or required. The standard minimum height to ride Tilt-A-Whirl is 46 inches, a requirement set by the manufacturer and determined by safety regulations, not the typical height of other riders of the same age. 

How do I know how my students are doing?

Our Tilt-A-Whirl story can help illustrate why a 3rd grader with a 700L measure can be both within the 50th-75th percentile according to the norms on the Lexile Grade Level Charts and demonstrate only partial command of your state’s standard. 

• Grade Level Charts (Norms): The information on the Grade Level Charts represent student norms. This data came from a sample of over 3 million students across the United States and Virgin Islands who were administered tests from 2010-2019 that reported Quantile and Lexile measures. The norms on the Grade Level Charts reflect how students compare to their peers, like a growth chart.
• State Standards: On the other hand, state standards outline the learning expectations or requirements for each grade level, similar to the height requirement for the Tilt-a-Whirl. Standards are typically set by the state’s Department of Education and do not indicate how students compare to each other.  

Interestingly, just as height standards may vary from ride to ride, education standards may also vary from state to state. Be sure to check your state’s Department of Education website to find your specific state’s standards. To see how your students’ measures compare to their peers nationally, you can find the Lexile Grade Level Charts and Quantile Grade Level Charts located in the Resources dropdown menu.

Using Grade Level Charts Your Classroom

Now that you understand the norms presented on the Lexile and Quantile Grade Level Charts, you can use this resource to create instructional groups and select targeted materials that meet the personalized learning needs of your students and improve student outcomes. You can also use these charts to communicate with parents about their student’s reading and math growth, just as doctor’s do when discussing a child’s height each year.
Are you still spinning on the difference between norms and standards? Watch this video from our Educator Academy to learn more. If you are interested in deepening your understanding of the Lexile and Quantile Frameworks and want to see how other Hub tools and resources can help with classroom instruction, enroll in the Educator Academy. The Lexile & Quantile Educator Academy offers self-paced professional learning courses for K-12 educators. Visit the Professional Learning page in the Support section for more details or sign up for a course today.