The robin is one of the animals we've talked about this year. Most of our work around this has centered around the suggested activity of building a "bird nest" and papier mache bird, which the girls have loved. But finding something that translates into taking action, especially in the dead of winter, is challenging.
I found this activity on education.com. Technically it's for "Christmas Cookies" for the birds - but you could easily make it using any shape or cookie cutter - or even cut circles with the lip of a cup. We beta-tested it at home with a first-grader and preschooler, and the project took less than 15 minutes with clean-up. (Plan accordingly with the size of your group!)
Supplies needed are bread (they recommend slightly stale, and I agree - ours was too soft to hang), peanut butter or shortening, birdseed, sunflower seeds and/or raisins, cups or cookie cutters, straws (1 per three girls), knives to spread peanut butter with (1 per 2-3 girls) and yarn or twist-ties from garbage bags.
Simply put, you cut out bread into shapes, poke a hole in it with the straw, slather it with peanut butter and cover with birdseed. (We used raisins and sunflower seeds.) Setting these up on cookie sheets made for easy clean up!
To finish it, we used trash bag ties (which had been in my drawer for years) pulled through the hole. We're letting it dry before we attempt to hang it outdoors, so you may want to consider sending the projects home on scrap pieces of cardboard so projects don't break en route.