Book 16 activities
Try it at home: 150 science activities from Book 16
Every question in A Million Whys Book 16, The Desert Expedition, ends with a "Think like a scientist" idea. Here they are in one place. Each one links to its question page, with the video and the full answer.
Expedition 1: Desert Worlds & Wind-Carved Land (25)
1. What Counts as a Desert?
Set a straight-sided jar outside for a month and measure how much rain collects. A desert gets less than one inch a month on average. Is your yard wetter or drier than a desert?
Do this with a grown-up2. Are All Deserts Hot and Sandy?
Look at a world map or globe with a grown-up and find three deserts. Guess whether each is hot, cool, or cold, then read about them to check your guess.
Do this with a grown-up3. How Big Is the Sahara?
With a grown-up, use a map app to compare the Sahara with the place you live. How many times could your province or state fit inside it?
Do this with a grown-up4. Why Was the Sahara Green Thousands of Years Ago?
Spin a globe and tilt it a little toward a lamp, then away. Notice how the light falls on different places. A tiny tilt change over thousands of years can shift where the rain goes.
Do this with a grown-up5. Why Is the Atacama One of the Driest Places on Earth?
Dampen two paper towels. Put one in a plastic bag and the other flat on a plate in a warm, breezy spot. Check them after an hour. Which dried out? Dry, moving air pulls moisture out of things fast, which is why dry places feel so parched.
6. Why Is Antarctica Called a Desert Even Though It Is Covered in Ice?
Compare two numbers with a grown-up online: the yearly rainfall of the Sahara and of the middle of Antarctica. Which one is a little wetter, and what surprises you?
Do this with a grown-up7. Why Are Desert Sand Grains So Round and Frosted?
With a grown-up, look at sand through a magnifying glass indoors or in the shade. Never point a magnifying glass at the Sun. Are the grains round or sharp? Sprinkle a pinch on dark paper and see which grains shine.
Do this with a grown-up8. How Do Sand Dunes Form?
Gently pour dry sand or salt from a spoon onto a tray and watch how a cone builds up. Then blow softly across it. How does the pile change shape?
9. Why Do Dunes Have a Gentle Slope on One Side and a Steep Slope on the Other?
Make a sand pile in a baking pan and tilt the pan very slowly. Watch the sand slide at one fixed angle. That angle is what shapes a dune’s steep side.
10. Why Do Dunes Slowly Move Across the Land?
Draw a dune as a triangle in your notebook. Add arrows for the wind and the sliding sand. Then draw it again as it would look a year later, shifted to the right. Show a grown-up your drawings.
Do this with a grown-up11. Why Do Desert Rocks End Up in Strange Wind-Carved Shapes?
Rub a bar of soap with a rough sponge, then with a soft cloth, and compare. Rough scrubbing wears the surface faster, just like blowing sand.
12. How Do Stone Arches Form in the Desert?
Look at pictures of arches with a grown-up. Draw one and mark where you think rain would soak in. Why would the thin parts break first?
Do this with a grown-up13. What Is Desert Pavement?
Fill a tray with fine sand mixed with small pebbles. Blow gently across it and see which pieces move and which stay. The stones that stay act like pavement.
14. Why Are Some Desert Rocks Coated in a Dark, Shiny Skin?
Cover a pale paper “rock” with dark crayon, then gently scratch a picture through it with a dull craft stick. The light paper shows through, just like the light rock under desert varnish.
15. How Can Salt Break a Rock?
Dissolve several spoonfuls of salt in warm water, with a grown-up. Dip a paper towel strip, hang it on a cup rim, and watch crystals grow as it dries.
Do this with a grown-up16. Why Do Some Deserts Have Flat White Salt Plains?
Fill a shallow dish with salty water and leave it in a sunny window for several days. What is left behind once the water has gone?
17. Why Does Dry Mud Crack Into Puzzle Pieces?
Spread a thin layer of mud or a mix of flour and water on a plate and let it dry for a day or two. Watch the cracks form and count how many pieces you get.
18. Why Are Desert Rocks So Often Red, Orange, or Pink?
With a grown-up, put a steel wool pad on a plate and spray it with water. Wear gloves because steel wool can poke fingers, and wash your hands afterward. Check it each day to watch orange rust form.
Do this with a grown-up19. Why Do Fossils of Sea Creatures Turn Up in Some Deserts?
Look at a photo of a fossil shell with a grown-up. Make your own by pressing a shell into modeling clay, then remove it to see the imprint it leaves.
Do this with a grown-up20. How Does Wood Turn Into Stone?
Hold a stick and a rock of the same size. Which is heavier? Petrified wood weighs like the rock, not like the stick, because stone took the place of the wood.
21. Why Do Giant Sandstorms Roll Across Deserts?
Stay indoors and picture a sandstorm. List three things you would do to stay safe. Tell a grown-up your list. In a real storm, people head inside and cover their faces.
Do this with a grown-up22. How Can Desert Dust Blow Across a Whole Ocean?
Tear tissue paper into tiny bits and put them in a small pile on a table. Blow gently across them from the side, away from anyone’s face. See how far they travel. Now imagine winds a hundred times stronger.
23. Why Are Deserts Good Places to Find Meteorites?
Hide a few dark pebbles on a light cloth and a few in a patch of grass. Ask a friend to find them. Which place is easier for spotting dark stones?
24. Why Does the Desert Sky Seem to Sparkle with Stars at Night?
Visit a dark spot with a grown-up on a clear night. Count how many stars you see in a patch of sky as big as your fist held at arm’s length.
Do this with a grown-up25. How Do Scientists Use Deserts to Practice for Mars?
Build a cardboard rover with paper wheels. Roll it over a tray of sand and a tray of smooth paper. Which surface is trickier for your rover?
Expedition 2: Surviving Heat, Chill & Thirst (25)
26. How Do Living Things Stay Cool in a Place with No Air Conditioning?
Make a “cool tricks” list with three columns: hide, reflect, and release heat. Add one animal or plant to each column as you learn about them in this book.
27. Why Is It So Much Cooler a Few Feet Underground in a Desert?
Use two thermometers. Bury one two inches deep in a cup of sand, and lay the other on top of the sand in the same sunny spot for an hour. Which one reads cooler? Why would a burrow help an animal?
28. How Do Desert Hunters Find Food on a Dark Night?
Sit in a chair while a friend stands across the room and softly rubs two fingers together. Close your eyes and point to where the sound is. Try again from different spots.
29. Why Do Big Ears Help Some Desert Animals Cool Off?
Trace your hand on paper and cut it out as a pretend ear. Wave it in front of your face, with a grown-up watching. Moving air carries away some warmth, a bit like a cooling fin.
Do this with a grown-up30. Why Are So Many Desert Animals Pale or Sandy Colored?
Cut a sand-colored paper animal and a bright blue one. Place both on a tray of sand and step back. Which one is easier to find from across the room?
Do this with a grown-up31. Where Do Desert Animals Find Water If There Is No Pond?
Weigh a handful of raisins, then soak them for an hour and weigh them again. Where did the extra weight come from? Dry food is dry, but juicy food holds water.
32. How Can a Kangaroo Rat Live Without Ever Taking a Drink?
Put a damp sponge piece in a closed jar and another on an open plate. Check them tomorrow. A closed burrow keeps moisture in the same way the jar does.
33. How Does a Beetle Collect Drinking Water From Fog?
Hang a clean, dry cloth in a steamy bathroom (with a grown-up present) and watch tiny droplets form on it. Droplets gathering on a surface is the beetle’s trick at work.
Do this with a grown-up34. Why Does Dry Air Make You Feel Thirsty So Fast?
Breathe onto a cold mirror or window with a grown-up and watch it fog. That fog is water from your breath. Wipe it away and breathe again.
Do this with a grown-up35. Why Should You Sip Water Often on a Hot Day Instead of Waiting Until You Are Very Thirsty?
Plan a hot-day kit for a family trip: a water bottle, a hat, sunscreen, and a shady rest spot. Show it to a grown-up and ask whether they would add anything.
Do this with a grown-up36. Why Is the Afternoon Often the Hottest Part of a Desert Day?
With a grown-up, check an outdoor thermometer at 9 a.m., noon, 3 p.m., and 6 p.m. Write down the numbers. Which time was the warmest?
Do this with a grown-up37. Why Is Sand Too Hot to Walk on at Midday?
On a warm, sunny day, put a dark cloth and a white cloth in the sun for ten minutes. Then feel each one with the back of your hand, briefly. Which one soaked up more heat?
38. How Do Animals Stay Warm on a Cold Desert Night?
With a grown-up, fill two mugs with warm (not hot) water. Wrap one in two socks and leave one bare. After 20 minutes, touch each. Trapped air is a great blanket.
Do this with a grown-up39. Which Deserts Get Freezing Winters, and Why?
Find the Gobi Desert on a map with a grown-up. Compare its winter temperature with your own town. Which is colder?
Do this with a grown-up40. Why Does Snow Sometimes Fall in Deserts?
Put a tray of crushed ice in a shady spot and watch how fast it melts. Ask yourself how quickly a thin dusting of snow would vanish in a sunny desert.
41. Why Do Lizards Switch Between Sun and Shade All Day?
Watch a lizard, bug, or butterfly from a distance for ten minutes with a grown-up. Notice whether it chooses sunny or shady spots. Never touch or chase wildlife.
Do this with a grown-up42. Why Do Some Lizards Lift Their Feet One at a Time on Hot Sand?
Stand on a cool floor in socks and lift one foot, then the other, like the lizard. Make up a dance that gives each foot a short break.
43. Why Do Saharan Silver Ants Run on Such Long Legs?
Draw one ant with short legs and one with long legs walking on hot sand. Which ant holds its body farther from the sand? Why would that help?
44. How Do Birds Cool Off Without Sweating?
Wet the back of your hand with a few drops of water and blow gently across it. Does it feel cool? Birds cool off in a similar way when water evaporates from their mouth and throat.
45. Why Does a Roadrunner Sunbathe in the Morning?
Hold up a dark paper and a white paper to the morning light for a few minutes. Touch each gently. Which one is warmer? Dark colors absorb more light energy.
46. What Is Summer Sleep, and Which Animals Do It?
Draw a snail on a rainy day and a snail in a dry spell, sealed in its shell. Which weather would make a snail want to rest in your area?
47. Why Do Some Desert Insects Have Waxy Skin?
Put one drop of water on a waxed paper square and one on regular paper. Watch what each does. The wax keeps water from sinking in, just as insect wax keeps water from leaking out.
48. Why Are There So Few Clouds Over Most Deserts?
For a week, look up at the sky each morning. Record whether it is clear, partly cloudy, or cloudy. Count how many clear days you get. Never look straight at the Sun.
49. What Happens to a Body That Is Too Hot, and How Can You Help?
Create a poster with three steps for a hot day: get into shade, sip water, and tell a grown-up. Put it on the fridge.
Do this with a grown-up50. Where Is the Hottest Place on Earth, and How Hot Does It Get?
Compare 134 degrees Fahrenheit with a hot bath, a summer day, and your body at 98.6 degrees. Put the numbers in order on a number line you draw.
Expedition 3: Plants That Beat the Dry (25)
51. How Do Plants Survive in Places Where It Almost Never Rains?
Draw a desert plant with at least one water trick. Label the trick, like a thick stem, deep roots, or a seed waiting under the sand. Then explain it to someone at home! Share what you discover with a grown-up.
Do this with a grown-up52. Why Do Many Desert Plants Have Tiny Leaves or No Leaves at All?
Pour the same amount of water into a wide dish and into a narrow cup. Leave them in a warm spot for a day. Which has less water left? A big surface loses water faster, like a big leaf.
53. Why Do Some Desert Shrubs Send Their Roots Down 50 Feet or More?
Draw a mesquite tree with a long taproot on a tall sheet of paper. Tape two sheets together if you need to. How much space does the root need compared with the tree?
54. Why Do Some Desert Plants Spread Their Roots Wide but Shallow?
Pour a little water onto a tray of dry soil and see how deep it soaks in after a minute. A wide shallow root net would catch it before it sinks or spreads.
55. Why Do Desert Wildflowers Bloom All at Once After a Rare Rain?
Plant a few wildflower or bean seeds in two cups of soil. Water one every day and keep the other dry. Which seeds sprout? Seeds need water to wake up.
56. How Can a Seed Wait for Years Until It Rains?
Soak a dry bean in water overnight and compare it with a dry one. Which is softer and bigger? Soaking is the first signal that tells a seed to wake up.
57. Why Does the Creosote Bush Smell Like Rain?
Crush a few fresh mint or herb leaves between your fingers and sniff. Leaves hold smelly oils in tiny pockets, and creosote leaves do the same.
58. How Can a Ring of Bushes Be 11,000 Years Old?
Place a coin on a table and surround it with a ring of other coins to model the clone. The center is old and the outer coins are the young shoots.
59. How Does a Joshua Tree Depend on One Little Moth?
Draw a picture of a moth and a flower with an arrow each way showing what they give one another. What does the moth get, and what does the tree get?
60. Why Do Some Desert Plants Have Fuzzy or Silvery Leaves?
Look at a fuzzy leaf, such as lamb's ear, with a magnifier. Put a drop of water on it, and one on a smooth leaf. Which drop sits up higher? Ask a grown-up to help! Share what you discover with a grown-up.
Do this with a grown-up61. Why Do Some Desert Plants Open Their Pores Only at Night?
Think of a window: open it when it is cool and shut it when it is hot. How is that like the plants’ trick? Share your idea with a grown-up.
Do this with a grown-up62. Why Are Aloe Leaves So Thick and Gel-Filled?
With a grown-up, look at a houseplant with thick leaves. Gently press one with a fingertip to feel how firm and water-filled it is. Do not break the leaf.
Do this with a grown-up63. Why Do Some Desert Plants Look Like Pebbles?
Pick up a few pebbles outside and draw one that could pass for a plant. Hide it among real pebbles for a friend to find.
Do this with a grown-up64. Why Does the Ocotillo Grow Leaves Only After It Rains?
Make a pipe-cleaner “ocotillo” with bare sticks. Add paper leaves with tape on a rainy day and take them off on a dry day. Leaves on and off is the plant’s trick.
65. How Can a Resurrection Plant Come Back to Life?
Put a dry, crumpled paper flower or a dried tea leaf into a bowl of water and watch it unfold. It is not alive, but it shows how water can change shape.
66. Why Does a Tumbleweed Roll Across the Land?
Roll a crumpled ball of paper across the floor with a puff of air from a straw. Poke a few rice grains inside to see how seeds fall out.
67. Why Do So Many Desert Plants Have Thorns or Spines?
, with a grown-up! Look at a photo of a spiny plant. Count how many spine clusters you can find on one inch of the plant. Never touch spiny plants! Share what you discover with a grown-up.
Do this with a grown-up68. What Is the Welwitschia, the Namib Plant That Lives for Centuries?
Tape a long paper strip to the floor and draw a welwitschia leaf on it. Add one more inch of leaf each day. How long does it get in a week?
69. How Do Desert Plants Avoid Crowding Each Other?
Draw a dry-land map by placing dots for plants so that no two touch. Then draw a circle around each dot for its root space. Do the circles overlap?
70. Why Do Some Desert Leaves Stand on Edge Instead of Lying Flat?
, with a grown-up! Hold a paper leaf flat toward a flashlight, then turn it so its edge faces the light. Notice how the shadow changes. The smaller shadow shows less light caught. Share what you discover with a grown-up.
Do this with a grown-up71. Why Do Big Cacti Have Pleated Sides?
Fold a paper fan and open it slowly. Notice how it expands, and think how a cactus does that. How does the fold let it get bigger and smaller?
72. How Do Mesquite Trees Make Poor Desert Soil Richer?
With a grown-up, gently dig up a clover plant from a lawn and rinse the roots. Look for tiny lumps. Those nodules hold the helpful bacteria.
Do this with a grown-up73. How Do Animals Help Desert Seeds Spread?
Press a few sticky or burr seeds, or a piece of hook-and-loop tape, onto a sock outside. Which seeds stick? This is how some plants hitchhike. Do this only on seeds a grown-up approves.
Do this with a grown-up74. Why Do Many Desert Plants Taste Bitter or Smell Strong?
With a grown-up, smell a few kitchen herbs such as basil, mint, and rosemary. Which smell is strongest? Plants make these smells for protection, not for us.
Do this with a grown-up75. What Useful Things Do People Get From Desert Plants?
Check labels at home for aloe, jojoba, or date ingredients. Find one thing made from a desert plant and tell a grown-up what you found.
Do this with a grown-upExpedition 4: Animals of Sand & Scrub (25)
76. How Does a Sidewinder Snake Travel Across Loose Sand?
Pretend to be a sidewinder: lift your hands and feet and slide sideways across a carpet, touching only with two points at a time. Is it harder or easier than walking?
77. Why Does the Thorny Devil Have Spiky Skin and Drink with Its Feet?
Dip the corner of a paper towel in water and watch the wetness climb upward. That climbing is capillary action, the same force that moves water along a thorny devil’s skin.
78. How Do Desert Tortoises Survive Years of Dry Weather?
Fill a baking tray with sand in a sunny spot. Place a toy turtle on top and bury another about three inches deep. After 15 minutes, feel the sand near each one with a grown-up. Which spot is cooler? Why would a tortoise want a burrow?
Do this with a grown-up79. Why Does the Gila Monster Store Fat in Its Tail?
Draw a Gila monster, shading its tail extra thick. Under it, write the words “fat battery.” What other animal do you know that stores energy in its body?
Do this with a grown-up80. How Do Spadefoot Toads Live in a Desert?
Seal one damp sponge in a zip bag and leave another one out in the open. Check both tomorrow. Which is still damp? A spadefoot’s skin cocoon works like the bag.
81. Why Do Fairy Shrimp Hatch From Dry Dust After a Rain?
Look closely at a rain puddle with a grown-up after a storm. Do you see anything tiny moving? Never drink the water, and wash your hands after touching it.
Do this with a grown-up82. How Does a Scorpion Find Its Way and Its Food in the Dark?
Place a plate on a table. Have a friend tap lightly with a finger on the other side of the table while you rest your hand on the plate. Can you feel the direction of the taps?
83. How Do Jackrabbits Escape Fast Hunters?
Play a gentle tag game with friends in which the runner must zigzag. Is a zigzag path harder to catch than a straight run?
84. Why Do Desert Bighorn Sheep Climb Steep Cliffs?
Compare a rubber shoe sole and a smooth wooden spoon on a slightly tilted board. Which grips better? That is the secret of the bighorn’s hoof pads.
85. Why Can a Horned Lizard Look Like a Flat Rock?
Cut a lizard out of sandy paper and place it on a patch of gravel. Walk away and see from how far you can spot it. Move it to a different background and try again.
Do this with a grown-up86. How Does the Tiny Elf Owl Find a Home in a Cactus?
Find a picture of a cactus nest hole with a grown-up. Draw a cutaway with the owl inside. Why is a hole inside a thick cactus cooler than the air outside?
Do this with a grown-up87. Why Does the Sand Cat Have Furry Feet?
Wear thick socks and walk on a carpet, then walk in bare feet. Notice how the socks change the grip and feel. Fur works like a built-in sock for the sand cat.
88. Why Do Honeypot Ants Have Balloon-Shaped Bellies?
Fill a balloon with a little water and feel how its shape changes. Imagine it is a honeypot ant’s belly, swelling to store food for the colony.
89. How Do Sandgrouse Carry Water to Their Chicks?
Soak a small sponge and a toothpick in water. Which carries more water? Feathers coiled like a sponge hold more.
90. How Does the Sandfish Lizard Swim Through Sand?
Push a smooth spoon and a rough spoon through a bowl of dry sand or rice. Which slides more easily? Smooth surfaces slip better, like the sandfish’s scales.
91. Why Do Jerboas Hop on Two Long Legs?
Hop across the room with your feet together and arms held out to the sides. Then hop on one foot. Which gives you better balance? Your arms are like a jerboa’s tail.
92. How Do Bats Help Desert Plants?
Pretend to be a bat: dip a cotton swab in flour and tap it on a “flower” made of paper. See how powder moves from one place to another.
93. Why Does the Bilby Dig So Many Burrows?
Dig a short tunnel in a sandbox or a pile of sand with a spoon. How deep can it go before the walls fall in? Try again with damp sand. Damp sand holds a tunnel better.
94. How Do Desert Elephants Live Where It Hardly Ever Rains?
Dig a hole in a sandy spot at the playground or beach with a grown-up. Does the sand get damper as you go deeper?
Do this with a grown-up95. How Do Desert Animals Keep Sand Out of Their Eyes and Noses?
With a grown-up, wear clear safety goggles and stand in a gentle breeze. Think about how animals’ eyelids work like goggles. Draw your own animal with built-in eye protection.
Do this with a grown-up96. How Do Scientists Find Out Which Animals Visit a Desert at Night?
, with a grown-up! Place a plain paper plate with a thin layer of flour on it outside overnight. Check for tracks in the morning. Who walked by? Share what you discover with a grown-up.
Do this with a grown-up97. How Can You Read Animal Tracks in the Sand?
Press your hand and your shoe into damp sand or soft dough. Compare their shapes. Then make a track with only two fingers. What different stories could each tell? Share what you discover with a grown-up.
Do this with a grown-up98. Why Do Desert Geckos Have Such Big Eyes?
Dim the lights and look at your pupils in a mirror with a grown-up. Have the grown-up switch on a room light and watch your pupils shrink. Never stare at a bright bulb. Your eyes change like a gecko’s.
Do this with a grown-up99. Why Are Desert Tortoise Burrows Like Apartment Buildings?
Draw a cutaway tortoise burrow with three different animals living in it. Give each a name and a reason for being there.
100. Who Eats What in a Desert Food Chain?
Draw a food chain with arrows going from the plant to a seed eater to a hunter. Add a desert animal you learned about. Where does it fit?
Expedition 5: Hidden Water & Rare Rain (25)
101. Where Does an Oasis Get Its Water?
Fill a tray with sand and slope it, then pour water on the high end. Where does the water go? The low spot that stays wet is where an oasis could form.
102. Why Can Palm Trees Grow at an Oasis?
Draw an oasis farm with three layers: tall palms, middle-sized trees, and low vegetables. Add the Sun’s rays and show where the shade falls.
103. What Is a Wadi?
Draw a map of a wadi with the dry bed in the middle, plants along the sides, and arrows showing where floodwater would run.
104. Why Can a Dry Riverbed Fill with Water on a Sunny Day?
Pour a cup of water down a hard, dry plastic tray tilted slightly. Watch how quickly it runs off. Hard, dry ground can’t soak up water. Remember to keep away from dry washes if storms are near.
105. How Does Water Hide Underground in a Desert?
Fill a cup with sand, then slowly pour in water until it just covers the sand. Notice that water fills the gaps between grains. Squeeze a sponge to see another water holder.
106. What Is Fossil Water, and Why Is It So Old?
Imagine a bank account that people use but never refill. Draw a bar showing how fast the account would empty if you spent 10 coins a day from 100 coins.
107. How Does a Spring Flow Out of Dry Ground?
, with a grown-up! Ask your grown-up to poke a small hole in the bottom of a plastic cup. Fill the cup with damp sand, and add water on top. Watch where the water comes out. That is a model spring! Share what you discover with a grown-up.
Do this with a grown-up108. Why Do Tiny Fish Live in Only One Desert Pool?
Draw a tiny pool with a dot for your pupfish. Draw a larger circle around it showing the desert. Why would a pool this small be easy to damage?
109. Why Do Tiny Pools in Desert Rocks Teem with Life?
Fill a shallow bowl outside with a little rainwater or tap water. Watch for a few days. Does anything visit or grow there?
Do this with a grown-up110. Why Does Fog Roll Into Some Coastal Deserts?
Pour cold water into a clear glass on a humid day. Watch how a mist forms on the outside. Warm, moist air that meets a cold surface turns to droplets.
Do this with a grown-up111. How Do Fog Nets Catch Water?
Spray a fine mist toward a window screen or net from a distance, with a grown-up. Do drops form on the strings? Let them run down into a cup.
Do this with a grown-up112. Why Do Desert Rains Come in Short, Heavy Storms?
Pour a cup of water slowly on a tilted plate, then pour the same cup in a big splash. Which soaks into a sponge more? Gentle rain soaks better than a sudden downpour.
113. Why Does Rain Sometimes Disappear Before It Hits the Ground?
Put a drop of water on a dry plate in a sunny window and time how long it takes to vanish. Dry air takes water quickly, just like on a desert day.
114. Why Doesn’t Desert Soil Soak Up Rain Well?
Pour water on packed clay or hard dirt and on loose potting soil. Which one soaks it up faster? Keep the experiment on a tray.
115. What Is a Monsoon Season in a Desert?
Draw a calendar strip for a monsoon summer. Mark mornings with a sun and afternoons with a storm cloud. Why do clouds grow in the afternoon?
116. Why Can Desert Mornings Be Covered in Dew?
, with a grown-up! In the early morning, check grass or a car roof for dew. Wipe up a handful of dew onto a paper towel. How much did you collect? Share what you discover with a grown-up.
Do this with a grown-up117. How Do Desert Animals Sense That Rain Is Coming?
Notice animals and plants near your home before a storm for a week. Does your dog, a bird, or a flower change in some way? Keep notes.
118. Why Are Some Desert Lakes Saltier than the Ocean?
, with a grown-up! Stir salt into a glass of water until no more dissolves. Gently lower a raw egg into plain water, then into the salty water. Which one floats higher? Share what you discover with a grown-up.
Do this with a grown-up119. Why Do Some Desert Rivers Vanish Into the Sand?
Pour a cup of water slowly onto a mound of dry sand in a pan. Watch how fast it vanishes. Where does the water go?
120. How Can a River Cross a Desert Without Drying Up?
Find the Nile on a map with a grown-up. Trace it from the start to the sea. What kind of land is on either side of the river?
Do this with a grown-up121. How Can a Lake Appear in the Desert After a Big Rain?
Draw two pictures of the same basin, one dry and one with a lake. Add three animals that might appear when the water arrives.
122. How Do Scientists Find Water That Is Hidden Underground?
Drop a few marbles in a jar, then pour in water. Tap the jar and see how water fills the gaps between marbles. Imagine the marbles as rocks and the gaps as holes holding water.
123. Why Does Some Desert Water Taste Salty or Bitter?
Taste test with a grown-up: sip plain water and then water with a pinch of salt. Notice how a tiny amount changes the taste. Rinse your mouth after.
Do this with a grown-up124. How Do Rocks Slide Across a Dry Lakebed?
Place a small block on a smooth tray with a thin layer of water. Blow very lightly. Does it slide more easily than on a dry tray?
125. How Can Old Lake Shorelines Show Up on Desert Mountainsides?
Fill a bathtub or sink, with a grown-up, and let some water out slowly. Notice the ring marks at different levels. This is how old shorelines tell stories.
Do this with a grown-upExpedition 6: People, Science & Care of Dry Lands (25)
126. How Can Covering Up Keep You Cooler in a Hot Desert?
On a warm, sunny day, stand in the shade. Hold a white cloth over one forearm while the other stays bare, for a few minutes with a grown-up watching. Which arm feels warmer? Shade and the air under the cloth are the secret. Take breaks and drink water.
Do this with a grown-up127. Why Are Many Desert Houses Made of Thick Mud Brick?
Wrap one ice cube in a thick towel and leave another bare on a plate. Check after 20 minutes. Which stayed icy longer? Thick material slows heat down, like adobe walls.
128. How Do Tall Wind Towers Keep Desert Houses Cool?
Stand a paper tube upright and hang a thin tissue strip just inside the top. Blow gently across the opening. Does the strip flutter upward? Moving air can pull more air along.
129. Why Are Old Desert Towns Built with Narrow, Winding Streets?
Place two blocks close together on a table and shine a flashlight across them from the side. Then move them far apart. Which setup leaves more shadow in the gap?
130. What Is a Qanat, and How Does It Bring Water to a Village?
Roll a sheet of paper into a tube and tilt it gently. Roll a marble through it. Gravity does the work, just like water in a qanat.
131. How Do Desert Farmers Grow Crops with So Little Water?
Poke a tiny hole in the bottom of a paper cup, set it on a plant pot, and fill it with water. Watch the slow drip reach the soil. Is it better than a big splash?
132. How Did Travelers Find Their Way Across the Desert Before Maps and GPS?
Step outside after dark with a grown-up and find the North Star using the Big Dipper. Which direction does it point to?
Do this with a grown-up133. Why Are Deserts Such Good Places for Solar Panels?
Cover half of a small calculator’s solar cell with your hand or paper. Does it still work? Panels need light, so shading them matters.
134. How Do Mirror Fields in the Desert Turn Sunlight Into Electricity?
, with a grown-up! Use a flashlight, not the Sun, and a small mirror. Bounce the light spot onto a wall. Move the mirror and watch the spot move. Never aim light at anyone's eyes. Share what you discover with a grown-up.
Do this with a grown-up135. How Do Desert Cities Store Water for Dry Times?
Count how many cups of water you use in one day at home for brushing your teeth, washing your hands, and drinking. Add them up. Which job used the most? How could you use less?
136. How Can Salty Water Be Turned Into Fresh Water?
With a grown-up, place a small cup in a bowl of salty water, cover the bowl with plastic wrap with a small stone on top, and leave it in a sunny spot. Check for fresh drops in the cup.
Do this with a grown-up137. What Is Desertification?
Pack soil on two trays, adding grass sprouts or moss to one. Tilt both and pour a little water over them. Which holds its soil better?
138. What Helps Hold Sand Dunes in Place Near Farms and Roads?
Place small toothpick “fences” in a tray of dry sand and blow gently across it. Does sand pile up behind the fence?
139. What Is the Crust on Desert Soil, and Why Shouldn’t You Step on It?
Make a “crust” by pressing a damp paper towel onto dry sand and letting it dry. Poke it gently with a finger. What happens to the sand underneath?
140. Why Do Rangers Ask Hikers to Stay on the Trail?
Draw a trail map of a made-up desert park. Mark places where you would stay on the path and places you would just look from a distance.
141. Why Do Paleontologists Love Deserts and Badlands?
Bury a few small toys in a tub of sand. Brush away the sand with a paintbrush to uncover them carefully. Which tool is better, a brush or a spoon?
142. Why Do Dry Places Keep Old Things From Rotting?
Place a slice of apple in a sealed bag in a dry place and another in a sealed bag with a damp paper towel. Keep both sealed, do not open or sniff them, and ask a grown-up to throw them away after a week. Which got moldy sooner?
Do this with a grown-up143. What Jobs Involve Studying Deserts?
Pick one desert job and write three questions that person might ask about a desert. Share them with someone at home.
144. What Do Scientists Pack for a Day of Fieldwork in a Desert?
Make a safety checklist for a day trip to a hot, dry place. Include water, hat, buddy, and a plan. Show it to a grown-up.
Do this with a grown-up145. How Can You Stay Safe on a Desert Hike?
Pack a pretend hiking bag with a grown-up and check each item against a list: water, hat, sunscreen, snack, map, whistle. What would you add?
Do this with a grown-up146. What Should You Do If You See a Snake or Scorpion Outdoors?
Practice with a friend: one person pretends to see a snake, and the other shows the steps , stop, back away, tell a grown-up. Run the drill twice.
Do this with a grown-up147. Why Do Some Desert Animals Need People’s Help to Survive?
Design a wildlife crossing with building blocks so that small animals can pass under a toy road. Test it with a toy car overhead.
148. How Can Kids Help Save Water at Home?
Put a cup under a slow-dripping tap, with a grown-up, for an hour. Measure how much water it collects. Multiply by 24 to see a day’s waste.
Do this with a grown-up149. Why Can the Desert Feel So Quiet?
Sit still for two minutes outside and listen. Draw an ear and write down every sound you hear around it. Do it again at another time of day.
Do this with a grown-up150. What Mysteries About Deserts Are Still Unsolved?
Write down your own big question about deserts. Then think of one way you could look for the answer, like reading, watching, or asking an expert.