You might think your 3 and 4 Year olds aren't ready to waltz but give them a context and they will love learning the basics! 

These dancers are in our 3 year old program and are trying this activity for the first time so I spent a couple of minutes providing a context for their actions.  I tell them that I was there late last night and the invisible spiders were out all over the studio.  The invisible spiders love bright colors so they crawl right on top of my mats.  By asking the dancers to help me squish the invisible spiders, I can achieve the big bend needed for a basic waltz.  I also tell them that we have to be sneaky when approaching the next spot so we need to go on our tiptoes. 

When they get a little bit older, I can take the spots away and just concentrate on the down, up, up of the waltz.  Once they master the pattern without the spots (usually in the 4 year old year), we work on squishing more quietly and smoothing out the quality of the movement and varying our tempo (in the 5 year old program).

These dancers did a great job alternating their bends on the first try.  If your dancers don't pick up on the alternating pattern on the first try, don't worry.  They will get better after a few weeks of practice.