By Donna Blomquist and Brittany Blomquist
LaSalle Public Library

Celebrate trees from April 15 to May 15, 2021 by joining the GLOBE citizen science community in the 2021 Community Trees Challenge: Science is Better Together!

Connect science and art using the GLOBE Observer: Trees to extend popular rock painting into your library STEAM program. Rocks provide an endless canvas for creativity – here are a few ideas to get you started.

One to two weeks before your program:

  1. Download the GLOBE Observer free mobile app (

2. Gather materials

Larger, flat-ish stones

  1. Larger stones are easier for little hands. Aim for at least 2” x 3.”
  2. Any stone that is predominately one-color is fine, dark or light, just adjust the color of your paint or marker accordingly.
  3. Try a home supply store or a landscaper to find good, smooth “river” rocks.

Acrylic paints or permanent markers

Paint brushes or applicators

Clear sealer to protect the art from the weather


  1. Use the Trees tool in the GLOBE Observer app to photograph and measure a favorite tree, and then upload your observation. Find your tree information in the GLOBE Observer app by going to the Trees home screen and selecting My Observations. Remember, always follow guidelines from your local officials, and only participate in GLOBE activities or use the GLOBE Observer app if it is safe to do so.

2. Clean and dry your stone. Use a blow dryer if you will be painting the stones right after washing.

3. Draw your tree on one side of the stone using acrylic paints or permanent markers. Wait for this side to dry.

4. Record tree data collected using GLOBE Observer on the other side of the rock, e.g., height, trunk circumference, date, latitude and longitude. It is a bit neater to use dots to shape the letters and numbers of your information. Be sure to use contrasting colors to the rock.

5. When the information has dried, use a clear coat to protect the designs. To be more environmentally friendly, use a brush-on clear coat or clear nail polish.

6. Use your stone to document details of a tree in your own yard by placing it at the base of the tree and refer to it when you measure the tree in the future (e.g., next season or year).

Other ways to use your rock art:

Paint your tree and give it a simple message (e.g., Be happy, Be kind, Share a smile).

Leave your message rock at the base of a favorite tree in a public place, e.g., park, forest preserve, a library bench, a bike rack.

Information to include on the back of your rock

  • Include message on your rock asking the finder to move the rock to a new public place and leave it for someone else to discover and share the kindness
  • Link to your library webpage, social media, or email. Ask finders to send a message that the rock has been found and relocated. LaSalle Public Library has tracked gratitude rocks to other cities! Watch a short video at:

Learn more about joining the GLOBE #trees Challenge HERE