No rain fell. Why is this leaf wet?
Look at the drops on the leaf and the nearby spider web.
Yes. Air holds invisible water vapor. Dew forms right on a cool surface when that vapor condenses into liquid drops. It does not fall from the sky like rain.
Try this. Point to where the drops sit. Imagine a drop growing there, instead of falling down.
The leaf faces a wide, clear sky. The grass is still.
Surfaces give off heat to the sky. On a clear, calm night, a leaf can lose heat and get colder than the air around it. Clouds and wind can slow that cooling.
Try this. Trace the leaf’s edge. Say the first command: “Cool the leaf.”
The air above the leaf looks clear. New beads cling to the leaf.
The water was invisible vapor in the air. Air touching the cool leaf cools too. At its dew point, it is cool enough that it cannot keep all its water invisible. Some vapor condenses into liquid dew.
Try this. Imagine clear air touching this leaf. Use “condense” to tell what changed.
Sunlight reaches the leaf. Fewer drops remain.
As the sun warms the leaf, liquid water evaporates back into invisible vapor. The water changes form; it does not vanish forever. A cold glass can collect drops on its outside for the same condensation reason: that water comes from the surrounding air.
Try this. Say two commands in order: “Warm the leaf. Watch the drops shrink.”
Before sunrise, Little Wonderer found tiny drops on a leaf. A spider web beside it wore shining beads. “Did I miss the rain?” Little asked. The path was dry. Big Wonderer knelt beside the leaf. “Let’s follow the clues back through the night.”
Which clue makes the drops a mystery?
The night had been clear and calm. The leaf gave off heat to the open sky. It cooled and could get colder than the air around it. Little began a list of nature’s instructions: “1. Cool the leaf.” Nothing had fallen from the sky.
Where did the leaf give off heat?
Air holds water vapor, water in a gas form we cannot see. Air touching the cool leaf cooled too. At the dew point, it was cool enough that it could not keep all its water invisible. Little added: “2. Wait for the air to touch it.”
What water was already in the air?
Tiny drops formed right on the leaf. Water vapor had begun to condense: it changed from a gas into liquid water. That water was dew. The cool spider web held beads too. “3. Look for tiny drops,” Little wrote. “They formed here. They did not fall like rain!”
Where did these drops form?
Little checked the order: cool the leaf, let air touch it, then notice dew. “My commands are like a little program,” Little said. “But nature does not read my notebook!” Big smiled. The instructions helped Little explain the changes, one step at a time.
Why does the order of the commands matter?
Sunrise warmed the leaf. The beads grew smaller as water began to evaporate: it changed from liquid back into invisible vapor. Little added one last command: “4. Warm the leaf.” The water was not gone forever. It had returned to the air. What would the next night bring?
Where can the water go after sunrise?
These are counts from Little’s notebook. Solve one question at a time.
The command “add 5 drops” makes a drawing pattern.
1. Little counts 38 dew drops on one leaf and 47 on another. How many drops are there altogether?
38 + 47 =
Add 8 and 7 ones. Trade 10 ones for 1 ten.
2. A spider web has 72 dew beads. After sunrise, 38 evaporate. How many beads remain?
72 − 38 =
Trade 1 ten for 10 ones. Subtract 8 from 12, then subtract the tens.
3. A leaf has 28 drops. Then 17 more form, and later 19 evaporate. How many drops remain?
28 + 17 − 19 =
First find how many drops there are after 17 form. Then subtract 19.
4. Little draws 4 rows of dew beads with 6 beads in each row. How many beads does Little draw?
4 × 6 =
Draw four equal rows. Add 6 + 6 + 6 + 6.
5. Little has drawn 27 drops and wants 60 in the notebook. How many more drops must Little draw?
27 + ___ = 60
Count up from 27 to 30. Then count from 30 to 60.
6. Follow Little’s drawing command: add 5 drops each time. The counts are 12, 17, 22. What count comes next?
12, 17, 22, ___
Repeat the same instruction: add 5 to the last count.
Choose one scene below. Write one command sentence for the leaf’s story. You may add a second step.
First, …tell the leaf what to do before dew forms
Then, …tell what to notice on the cool leaf
After sunrise, …tell what to watch as the leaf warms
Draw the leaf before or after your command. Add one label.
SAY IT FIRST. THEN DRAW OR WRITE.
A temporary space. Copy your words before closing or reloading; they are not saved or sent.
leafwater vaporcondensedewevaporatefirstthen
Read your sentence. Does it tell what to do, using a command such as Cool, Wait, Look, or Watch?
Welcome words, pointing, or a sketch. Connect cooling → condensation → dew. After sunrise, connect warming → evaporation → invisible vapor.
You can stop here.
Say a command for each step: Cool the leaf. Wait for air to touch it. Look for tiny drops. Warm the leaf.
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