Consider File Size!

Are your students complaining about slow download times when accessing PowerPoint slideshows in your Blackboard CE course? If so, you need to first understand file sizes. If you want to see a chart of equivalencies, e.g. how many kilobytes (KB) in a megabyte (MB), and so on, check out http://www.t1shopper.com/tools/calculate/.

The basics are obvious: it takes longer for a 5 MB file to download than a 1MB file and it takes longer for a 500 KB file to download than a 1 MB file. So smaller is better.

Also effecting the download time is the type of internet connection (ISDN, DSL, Cable, Dial-up and so on). You can determine your connection speed (it’ll be different in your office, on a laptop at Starbucks, or at home) by going to http://promos.mcafee.com/speedometer/test_0600.asp. Keep in mind that the access speed may vary each time you take the test (depending on factors such as time of day and network traffic). If you and/or your students are experiencing slow access, take the test several times (at different times when you might normally access the Internet) to get a sense of the connection speed at which you can expect to access online materials. You can also see the optimal speed for various types of connections by visiting http://support.primus.ca/en/dsl/speedtest.php (review the chart on the right side of the web page).

Your connection’s “optimal” speed is based on average network traffic between your computer and the server; obviously heavy network traffic or outages between your home/office and the Blackboard server (or any server on the Internet for that matter) can reduce the download speed (upload speed too).

Another factor is whether media is non-streaming (e.g. PowerPoint slideshows) or streaming (e.g. MP3 and Flash files). Streaming files start playing before the entire file is downloaded (so it appears to download faster) while non-streaming media must be completely downloaded before playing.

So, in a perfect world without heavy network traffic, without considering Blackboard or browser problems or any network disruptions, you can calculate the best possible download time for a file traveling from one location on a network to another by using the calculator at http://www.hp.com/hpinfo/abouthp/accessibility/webaccessibility/download_tool.html.

The calculator asks you to enter kilobytes, so remember that a one megabyte (MB) file is 1024 kilobytes (KB) and a 25 MB file is 25,600 KB. As an example, if you have a 25 MB PowerPoint slideshow (e.g. 25600 KB) and were using a DSL or T1 connection, it would optimally take 2000 seconds (or over 33 minutes) to download that single file. On the other hand, if the file were reduced in size to 1 MB (e.g. 1024 KB) using the same connection, it would take 80 seconds to download the file. Obviously slower Internet connections (ISDN, dial-up) would take significantly longer.

We’ve seen PowerPoint slideshows within Blackboard courses that range from 25 to 70 MB. In tomorrow’s tip, we’ll tell you how to reduce a PowerPoint slideshow file by 60-95%. Imagine how that will increase download times and reduce frustration!