I teach science to first, second, and third graders and have used this activity to succesfully teach about the physical properties of shape, size, and color. I got brown paper bags which I labeled "Physical Properties Bags"... but you could label "Adjectives Bag" Inside each bag I put various objects that had different shapes, sizes, textures, and colors. I closed the bags and before I distributed them to each pair of students we did a word wall where we verbal word wall where we talked about words that we could use to describe objects. For your first graders you might want to actually write your word wall.
I started the kids off by asking: What are some words that would describe the SHAPE of something in this bag? ... What are some words that might describe the SIZES of things in this bag? I didn't ask about color because that would have gone on for ages.
The directions: Students would work with a partner. They were not actually allowed to look in the bags. Each student was to close their eyes and reach into their back (taking turns). They were supposed to pick up an object in the bag feel it, describe it while their partner tried to guess what it was. Next, they pulled it out of the bag to see if they were right or not. Each child had a chance to pull out all the items from their bags. I only put in 10 items.
Once all the items were on the table, students had to use adjectives that described color, shape and size while the partner tried to pick out the object from their combined objects.
The activity was followed by a discussion... but could easily have been followed up by a shared pen if we'd had more time. The kids LOVED this activity and I was able to incorporate language arts with science.