Observe air and measure wind with clear units and directions

Learning goal: Investigate observable properties of air and describe wind using evidence about speed and direction. Earth's atmosphere is the surrounding layer of gases, commonly called air. Air is usually invisible, but its effects can be observed and measured. Not seeing a material does not mean that it occupies no space.

An adult can hold open a small paper bag, move it gently to collect air and close its opening by hand. Gently press the sides and compare with the flattened open bag. The enclosed air resists having its space reduced. This is a simple observation of air taking up space, not a measurement of how much air the atmosphere contains. Avoid putting bags over faces or using a popping demonstration.

Wind is moving air. A ribbon tied securely outdoors may move when air pushes it. The ribbon is visible; the air causing its movement may not be. Nearby obstacles and the ribbon's position can affect what is observed. One ribbon at a sheltered doorway does not describe wind conditions everywhere around a school.

An anemometer is an instrument used to measure wind speed. A wind vane indicates wind direction. Use an adult-operated classroom instrument or a supplied record to compare measurements. Record the unit along with a speed number, such as miles per hour. Five without a unit is incomplete information about speed, and numbers from different units cannot be compared as if they were identical quantities.

Wind direction is named for where the wind comes from. A north wind comes from the north and moves toward the south. The diagram shows north at the top and an air-movement arrow pointing south. The label north wind identifies the source direction, not the arrow's destination. A weather vane's pointed end typically points into the wind; do not confuse that instrument's orientation with a separate arrow showing the air's travel direction.

Differences in warming and energy transfer help cause air movement in the atmosphere. The sun supplies energy that warms Earth's surfaces unevenly; interactions between air and those surfaces contribute to changing conditions. At this grade, use observed warming and wind patterns to introduce the connection without claiming that a single classroom ribbon proves a complete atmospheric explanation.

Keep a short wind record with date, time, place, instrument, direction and speed with its unit. In an invented example, a reading changes from 3 miles per hour to 7 miles per hour at the same place. The second measured speed is greater. That record alone does not tell tomorrow's weather or prove the wind was constant throughout the interval.

Worked example 1: Infer from an effect. A safely held closed bag resists a gentle squeeze more than the open flattened bag. The comparison supports that enclosed air takes up space and resists compression. Do not describe the bag as containing nothing because its contents are not visible.

Worked example 2: Read direction correctly. On the illustrated north-up diagram, air travels downward from north toward south. Call it a north wind. Calling it a south wind because the arrow points south reverses the naming convention.

Worked example 3: Compare speeds. In the supplied invented record, 7 miles per hour is greater than 3 miles per hour. Both use the same unit. If another record says 7 without identifying its unit, request that information before making a precise comparison.

Guided investigation: Observe an adult's air-in-a-bag demonstration, then compare ribbon movement with a suitable wind instrument or labeled practice record. Record the place and time, because conditions can vary. Read the direction label and air-travel arrow separately.

Independent tasks: Describe evidence that air occupies space, identify the purpose of an anemometer and a wind vane, and interpret a north-wind diagram. Compare two speeds in the same unit and explain one limitation of a single observation.

Feedback: If an arrow's destination is used as the wind's name, trace where the air begins. If a learner treats a measured instant as an all-day report, add the observation time. Credit conclusions connected to the available evidence and stated units.