What You'll Need

1 clear, tall, airtight container (such as a large empty plastic jar with a screw top or a glass canister with an sealed lid)

potting soil

small plants (such as mosses, ferns, philodendron, pothos, African violets)

pebbles or broken flowerpot chips

filtering charcoal (not barbecue charcoal) Note: You can find this at pet stores.

2 small thermometers (about 4-5 inches long)

paper towel or cloth

water

1 clear tall container, bag of potting soil, small plants, bag of rocks, packet of filtering charcoal, 2 small thermometers, paper towel

What To Do

number 1

Wipe clean the inside of your container with paper towel or cloth.

A child wiping the bottom of a small clear cylindrical container with a white cloth.
number 2

Place a one-inch layer of pebbles in the container.

A hand reaching into a bag of small stones on a wood tabletop next to a small open cylindrical container.
number 3

Next, cover the pebbles with a thin layer of fine charcoal.

A child pouring black powdery material into the bottom of a small cylindrical clear container.
number 4

Then add about 1 inch of potting soil over the charcoal.

A child transferring soil with their hand from a bag into a small cylindrical clear container.
number 5

Create a little hole in the soil. Place one or two small plants in the terrarium. You may need to add a little more soil so the roots are covered.

Child's hand placing a plant inside glass container
number 6

Water the plants until the soil is moist but not soggy. (You may want do this over the sink or a large dish.)

Child pouring water from a container into a glass container with soil and a plant.
number 7

Place a small thermometer on the soil, near the edge of the container so it's easy to read the temperature.

Child placing a small thermometer in a cylindrical terrarium containing soil and a plant.
number 08

Cover your container with an airtight lid.

number 9

Place the terrarium in a window that's well lit, but not too sunny. Place the second thermometer next to the terrarium.

Cylindrical glass container with soil, a plant, and a thermometer inside sitting next to another thermometer outside
number 10

Over the next few days, observe your terrarium closely. If water droplets don't form on the sides, add a little more water. If mold develops, remove the top and leave it off for a few days to let the soil dry out a little. Chances are you won't ever need to water the soil because water from the leaves will form water vapor, then condense into water droplets inside the top.

A chart with three column headings: date and time, temperature inside terrarium, and temperature outside terrarium.

Observe and record how the plants grow inside your terrarium. Also keep a chart of temperature readings inside and outside the container. Was there a difference?

Why do you think that is? Compare your findings with a friend or classmate. You should find that the more sunlight a terrarium receives, the bigger the temperature difference inside and outside the terrarium.