I don't know if you would be interested in any of these, but here are some things of my third graders that I have put in the hall:
1.) I gave my children a picture of a plant cell (with each part labeled), put them into
groups of 4, and gave them multi-colored construction paper. Each group made their own plant cell using the picture as a guide. They turned out great!
2.) I did the same for the continents.
3.) We also did the life cycle of a butterfly.
4.) Here is an idea that might be less work for you:
Choose a die-cut that your class likes (mine chose butterflies). Make a die-cut of that
shape for each of your students. Put their picture and name on the die cut and laminate them. Hang them in the hall with a clothes pin underneath each one. I put a title up that says "Doing Our Very Best Work." The students are able to pin what they think is their best work underneath their name and picture. They can change out their papers any time that they want. They love it and it saves me time!