I'll freely admit that I may be conflating memories here, but I'm 99% certain this was 3-2-1 Contact, although I also watched The Electric Company and other educational programs at the time (somewhere in the late 1980s to early 1990s). It was a live-action segment (and, as was usual for the skit, was just one of several segments, although I'm pretty sure that it was more than one segment in the episode with one introducing the problem and another the solution). A group of kids (I don't remember anything about ethnicity, although given where I grew up in Kentucky, I suspect I would have noted it as odd if they weren't predominantly white) either discovered, or were shown, a furry alien that looked a bit like a tribble or a toupé. The creature reproduced rapidly, with the episode being about exponential growth. I had largely forgotten the episode until I read Children's sci-fi story about a group of British(?) school children who find an alien animal and it made me remember.
I have a vague association in my head of an episode in the same period of time involving building a box out of Lego blocks and calculating how many Lego one would need for N boxes, but I could say if it was the same episode or just one in the same year, or even whether that really was the same series.
