Bar charts are used to compare individual values or measures of categorical data. The objective of this activity is to teach your student how to read bar charts using data that may be inherently interesting to students of all ages.
Install SAS Graphics Accelerator.
Arrange the computer speakers correctly. Your student and the two computer speakers should form an equilateral triangle. Make sure both speakers are pointing directly at your student. Also, if your speakers have a “balance” setting, make sure the balance is set so that sound is evenly distributed between the speakers.
If you don’t have external speakers for your computer, your student can use headphones or ear buds. In that case, make sure your student is wearing them properly so when sound plays in the left speaker they hear it in their left ear.
Place the keyboard in front of your student so they can “drive” and perform the steps defined below.
Tip: If your student is using a screen reader, SAS Graphics Accelerator will use the screen reader’s speech facility to speak data values within charts. If your student is low vision and does not typically use a screen reader, they may benefit from SAS Graphics Accelerator’s ability to self-voice. To enable that feature, open the SAS Graphics Accelerator popup menu in the Chrome tool bar, activate the Options button, enable the self-voicing feature on the Options page, and activate the save button on the Options page.
Open the bar chart that compares the diameter of planets in our solar system.
If SAS Graphics Accelerator is installed, you should see an “Accelerate” button in the bottom right corner of the chart. If you don’t see the button, install SAS Graphics Accelerator and refresh the page in Google Chrome.
Activate the “accelerate” button. That should open the “sonification view” in a new browser tab.
If your student is running JAWS or NVDA with the default settings, their screen reader should enter Forms Mode automatically. If that does not happen, press Tab or Shift + Tab to move focus to the chart and then press Enter to enter Forms Mode.
When focus is on the chart and Forms Mode is enabled …
Press V until you hear “scan”. That ensures you are in scan mode rather than explore mode. Scan mode enables you to quickly scan the entire chart.
Press D until you hear “slowest”. We set speed to slowest for this chart because there are only a few bars.
Press Right Arrow once to play the entire chart from left to right. Point out that the pitch of each note represents the altitude of the corresponding bar on the Y axis. Also, point out that the position of each note between the left and right speakers represents the position of the corresponding bar on the X axis.
Invite your student to play the entire chart from left to right several times until she has satisfied her curiosity. If this is the first time she has explored data using SAS Graphics Accelerator, she may need some time to process the concept of representing spatial information using sound. She may also need some time to acclimate herself to the novelty of the sounds.
When your student is ready to proceed, ask her if she can hear the highest and lowest bars? Is there a pattern the chart? For example, maybe a trend up or down. Or, maybe a peak or valley.
Press C until you hear “terse”. The terse speech mode provides a succinct description of the X and Y values of each bar.
Press V until you hear “explore”. That will change SAS Graphics Accelerator from scan mode to explore mode. Scan mode enables your student to quickly scan the entire chart. However, explore mode enables your student to explore each individual bar in the chart.
Explore mode changes the behavior of the arrow keys. For example, while in scan mode your student could scan the entire chart by pressing Right Arrow. However, Right Arrow plays the next bar to the right in explore mode.
Here’s a few commands that your student can use to explore each bar in explore mode:
Invite your student to explore the chart using the commands listed above. As she plays each bar, she should hear a musical note as well as a verbal description of the X and Y value of each bar.
When your student is ready to proceed, ask the following questions …
Is Earth larger than Mars?
Is Earth larger than Saturn?
What is the largest planet?
What is the smallest planet?
Note: The last question is tricky because Mercury and Pluto play the same sound. They play the same sound because the scale of the Y axis is very large and there are a limited number of musical notes available on the Y axis. As a result, your student will need to listen to the speech description of the Y value to determine which of those two planets are the smallest planet.
Invite your student to practice using additional bar charts that compare fun facts about planets. Remember to scan the entire chart for the shape and trend before exploring each bar. Your student must master that skill before she can efficiently read charts that contain dozens or hundreds of data points.
How can your blind student independently create accessible digital bar charts that she can share with her general education teacher? That’s the topic of another blog post.
Activity: Create and share a simple bar chart
Activity: Reading line charts that show stock market data
Activity: Creating line charts from Yahoo finance stock market data
SAS Graphics Accelerator Tutorial #1: How To
SAS Graphics Accelerator Video Tutorial #2: Options
By Ed Summers