There is a valentine's craft a friend of mine (Shelly) created for me when I taught her daughter in first grade. I have since done this craft every year with my students to celebrate valentine's and the kids all LOVE it!
Animal Hearts is what I call this craft as it consists of making animals out of different sized hearts. Original, I know. :) My friend created an animal cheat heet for me (as I am not a great artist), which I still use to give my students ideas as to how to create different animals out of hearts. Most of the time, the students simply follow the samples, but every so often, I have a student or two who comes up with new animals on their own.
The prep work for this craft is entirely up to you. When I first taught this craft, I just had half heart templates that the students had to use to make the hearts they needed to fit their animals. This worked fine, but made the process longer and more difficult for my younger students (which means this technique could work really well with the older kids). Since then, I've found it easier to have parents help pre-cut tons of different sized hearts so that the students only have to cut out the large heart that serves as the base of their animal. This has worked out really well and I always have left over hearts to save for the following year.
Happy Crafting! :)