Because so many plants and animals live together in a small space, a tidal pool is a good focus for teaching the techniques of mapping, counting or estimating populations, graphing, and interpreting data. Generally, it's a good idea to teach basic mapping skills in the classroom, prior to your trip to the seashore.

Have the class form groups of three, four, or five. Assign one student in each team to be the recorder, one or two students to count or estimate populations of organisms, and one or two students to use field guides or identification sheets to identify organisms. Each group should find an interesting pool that is small enough to map easily. Or locate tidal pools in the spray zone, high tide zone, middle tide zone, and low tide zone. Assign groups to tidal pools located in different tidal zones (see "Tide Zones," pages 190-192.)

Brainstorm how to measure the depth and size (circumference) of the tidal pool. Use a meter stick to measure the depth in different locations. Measure the width and length of the pool. To measure the circumference, lay a thick string or cord the distance around the pool. Stretch the cord out on the shore and use a measuring tape to measure the length of the tape.

• How deep is the deepest spot in the pool?
• How wide is the pool? How long is the pool? What is the distance around the pool (circumference)? Use the knotted string.
• Identify all the plants and animals in the tidal pool.
• Describe in detail the physical characteristics of the tidal pool.
• Draw a rough sketch or map of the tidal pool. Include any distinguishing features such as rocks, crevices, a pebbly bottom, empty clam shells, and the location of plants and animals.
• Count or estimate the number of each species of plant and animal in the tidal pool. List these on a table.
• (Optional) Draw a rough sketch of the shore. Locate the tidal pool on the shore.