• flexible plastic bottle with cap (2-liter bottles)
• shoe box (with holes already punched in for the children -- one on each end, near the top; one on the long side of the shoe box, halfway down the side)
• thin wooden stick
• long piece of spaghetti
• thread
• crushed paper/newspaper
• paper fastener
• tape and scissors
• pencils and markers
• unifix cubes
• booklets to keep daily logs
• pictures of "real" barometers (to post near the center)
• directions in written and pictorial form

Procedures

1. When introducing the centers of the week to the students, model the procedures to make the bottle barometer. Be very specific and concrete and concise. Remind them that the directions will be posted by their center table and that these barometer's will be very important to make readings and observations of air pressure.
2. At centers, students will make a bottle barometer.
   1. Squeeze the air out of the bottle. Twist on the cap so that the bottle stays flat.
   2. Lay the flattened bottle in the box. Hold the bottle in place with crushed paper. Then push the stick through the holes in the box ends.
   3. Knot the thread around the spaghetti (this may be pre-prepared for the children). Put the paper fastener tabs around the spaghetti and through the hole in the box.
   4. Gently pull the thread over the stick, and tape it to the flattened bottle. [The spaghetti acts as a pointer. It should hang level and move up and down easily.]
   5. Draw a scale on the box with unifix cubes as measurement, and a marker. Mark the pointer's starting position with a dot.
   6. Keep the barometer inside, out of the sun and away from direct heat. The pointer moves up as air pressure rises, and down as air pressure falls. [Rising air pressure squeezes the bottle, flattening it even more. This pulls on the thread and raises the pointer. Falling air pressure lets the bottle expands slightly. The thread goes slack and the pointer drops.]
3. Find a place in the room to keep all the students' barometers. Students may even decorate and personalize their barometer. There should be set times during the day when students are to record their readings and observations of the weather at those times. Have students record their findings in scientific journals/logs.
4. After several days, discuss the findings of the students. What have they observed? Why do they think the stick moves? How is it related to air pressure? Compared to the pictures of the "real" barometers, how are theirs similar? What kinds of weather have they noticed when their barometer is at a certain reading?
5. Each day, students should record predictions in their logs, before taking the reading and observation of the weather.

Evaluation of Student Learning

1. Observe students at their centers as they make their barometers. Are they following directions in using all the materials and careful procedures? Have they noticed the pictures and written words around the center?
2. Listen to students' daily records and observations when it comes time to discuss what they have found. Have they been consistently keeping track and finding patterns? What have they found and written in their logs?
3. Listen to students make their predictions after they have a better understanding of the barometers. Do they follow their previous observations and readings? Are they able to make better guesses at the weather as time goes on and they are familiar with the patterns?