Algebra is not about learning to write in symbols (although they become useful later), algebra is about generalisations and patterns.
Beads on a string is a game that one can solve with trial and error, but it is more efficient to find patterns and rules. The ten tasks offer children plenty of opportunities to think, explore, reason and discover the pattern or rule.
The applet is developed by the Freudenthal Insitute, University of Utrecht (NL). For more maths applets from the Freudenthal Institute see Rekenweb (grade 1-7) or Wisweb (grade 7-10). The applet Beads on a string can be used with children in the age of 8-12.
You may want to add a few questions in between step 2 and 3.
If you have real beads in five colours and a string, the questions you and the students can ask are endless.