The Tickle-Prickle Club

A 3D tour of the skin for children about five to eight. It looks inside a tiny slice of it: new skin cells rising to the top, sweat on a hot day, goosebumps on a cold one, a tickle and a prickle sending messages to the brain, and a graze healing under its scab. Then fingerprints, and looking after your skin in the sun. Free, with no ads and no sign-ups.

What your child will learn

• Your skin is your biggest organ. It covers all of you, keeps germs out and everything else in, helps you stay cool and warm, and lets you feel the world.
• It has three layers: the epidermis on top, the dermis under it (with nerve endings, sweat glands, blood vessels and the roots of your hairs), and a fat layer at the bottom that keeps you warm and cushions bumps.
• New skin cells are made at the bottom of the epidermis and move up to the top, a trip of about two weeks to a month. You lose about 30,000 to 40,000 old skin cells every minute, as tiny flakes.
• On a hot day, sweat glands make sweat, which comes out through pores; as it dries it takes heat away. On a cold day, tiny muscles pull your hairs up straight: goosebumps.
• Nerve endings feel touch and pressure, heat and cold, itchiness and pain, and send messages up the nerves and the spinal cord to the brain. Touch something sharp or hot and a quick message makes you pull away.
• Your fingerprints formed before you were born, and nobody else's are the same, not even an identical twin's.
• When you graze your skin, platelets in your blood stick together, like glue, and dry into a scab. It keeps germs out while new skin grows underneath, and falls off by itself after a week or two (picking it can undo the repair).
• Melanin gives skin its colour: the more melanin, the darker the skin. Every skin needs looking after in the sun: slip, slop, slap, seek, slide.

How it works

Story. A lizard tells it in nine short chapters (lizards can't make their own body heat, so they warm up in the sun, and they shed their skin). Most of it happens in a close-up: a slice of skin, as if cut from the child's forearm, drawn big and simple. Each chapter has one ringed hero, and the chapter waits for it: a new skin cell rising to the top and flaking off, a drop of sweat coming out of a pore and drying, a message zipping from a nerve ending to the brain, and platelets sealing a graze. The echidna drops in with a prickle, and the possum for the fingerprints. At the end, the child slips on a shirt, slops on sunscreen, slaps on a hat, seeks the shade of a gum tree and slides on sunglasses, one at a time as the words say them. Every word is spoken and shown.

Explore. Turn the child round, peek inside (the patch of skin on the forearm lifts its layers apart), or tap any part to hear what it does. Tap the patch to open the slice of skin. Four buttons: Hot (sweat), Cold (goosebumps), Tickle (a feather's message up the arm to the brain) and Sunny (slip, slop, slap, seek, slide). Follow a skin cell takes a new cell from the bottom of the epidermis to the top, again and again, and What's this? shows the parts one at a time, including the slice.

Quiz. Six picture questions, read aloud, so it works before your child can read. A wrong answer greys out and they have another go; nothing is ever lost. Finishing brings a new animal for their My mob book, and a card of the words they now know.

The real words it teaches

The tour uses the real names for the parts, and says what each one means the first time. These are on the card at the end, and a tap on each says what it means. The hair follicle, the tiny muscles, the nerve endings, the blood vessels and platelets are named in the story or Explore, but kept off the card.

• Epidermis: the top layer of your skin, where new skin cells start.
• Dermis: the layer under it, with nerve endings, sweat glands and hair roots.
• Pores: the tiny holes that let sweat out.
• Sweat glands: the tiny parts that make sweat to cool you down.
• Melanin: what gives your skin its colour.
• Nerve endings: the tiny feelers in your skin.
• Fingerprints: the swirly ridges on your fingertips, yours alone.
• Scab: the crust that covers a graze while new skin grows.

For grown-ups: the skin, in detail

The slice of skin is drawn big and simple, and much thicker than real skin. What it shows, cartoon but true:

1. The epidermis is a stack of cells called keratinocytes. They are made by division in the bottom layer (the stratum basale), then pushed upwards, flattening and filling with the tough protein keratin, until they reach the top (the stratum corneum) as flat, dead cells that are shed. The same bottom layer holds melanocytes, which make melanin; skin colour depends mostly on how much melanin they make, not on how many there are.
2. The dermis is tough and stretchy, thanks to collagen and elastin. Its wavy top edge (the dermal papillae) interlocks with the epidermis; on the fingertips these ridges show on the surface as fingerprints. It holds the hair follicles, each with a sebaceous (oil) gland and a tiny arrector pili muscle; the sweat glands (the eccrine glands, coiled deep down, with a duct up to a pore); the blood vessels, which widen on a hot day (letting heat out) and narrow on a cold one; and several kinds of nerve endings: some for light touch and vibration, some for pressure and stretch, and free nerve endings for heat, cold, itch and pain.
3. The subcutaneous layer (the hypodermis) is mostly fat. It insulates, stores energy and cushions.
4. A graze heals in overlapping stages. Platelets gather and stick at the wound, and a mesh of fibrin threads forms a clot, which dries into a scab. White blood cells clear germs and debris; new cells grow in from the edges and from below, under the scab; later the new skin strengthens. The tour shows platelets, fibrin, the scab and the new cells.

Also left out of the slice: the different layers of the epidermis by name, the apocrine sweat glands (which start working at puberty), the lymph vessels, and the many kinds of nerve ending, drawn here as a few branched feelers.

What it practises

• My body. How the body works, and the real names of its parts: the heart's atria and ventricles, arteries and veins (the Lub-Dub Club).
  AC9S1U01 (Science, Year 1); AC9HPFM03 (Health and Physical Education, Foundation)

The codes are from the Australian Curriculum v9 (Foundation to Year 1). Each links to the official wording.

Things to try together

• Look at each other's fingertips with a magnifying glass. Are the swirls loops, whorls or arches?
• With eyes shut, stroke the back of a hand, then a fingertip, with a feather or a soft brush. Which feels it more? (Fingertips are packed with nerve endings.)
• After a run on a warm day, look for tiny drops of sweat on the skin. On a cold morning, look for goosebumps.
• Check the day's UV forecast together (the Bureau of Meteorology shows it) and choose your slip, slop, slap, seek and slide. The Cancer Council says to use all five when the UV index is 3 or above.
• The sheet to print has a slice of skin to label, boxes for your child's fingerprints, and "Hot or cold?" (a sunny beach, a snowy hill, a warm bath and an ice block).

For every child, and every skin

Skin comes in every colour, and the tour draws the child's skin in the tone chosen on the hub, in the slice as well. Melanin is described without any colour being better, and every skin, whatever its colour, needs looking after in the sun. Freckles, birthmarks, scars and differences in skin are simply part of skin; the tour says nothing about skin conditions. The graze is the only injury, kept small and clean, with no blood running, and the words are about healing. The prickle stands for anything sharp: the tour says "ouch" and "you pull away", and never shows a hurt.

• Every word is spoken and written, so it works with the sound on or off.
• It works with a keyboard: the arrow keys turn the child in Explore, and What's this? steps through the parts.
• Each hero has its own shape as well as colour: a skin cell is a rounded tile, sweat is a drop, platelets are discs, and a message is a zap.
• If your device asks for less motion, the camera cuts instead of flying, the page turns without the iris, and nothing spins or wobbles.

What's simplified, and why

• The patch of skin is drawn as a slab on the forearm, and its layers much thicker than real, so they can be seen at all. On a real forearm, the epidermis is thinner than a sheet of paper.
• "About a month" is KidsHealth's "about 2 weeks to a month" for a new cell's trip to the top; the guide gives the range.
• The story says "thousands of tiny flakes of old skin"; the guide gives KidsHealth's 30,000 to 40,000 a minute.
• Melanin is described without any skin colour being better; freckles and birthmarks are simply part of skin.
• The graze is the only injury in the series, kept small: no blood running, and the words are about healing.
• Nerve endings are drawn as a few branched feelers; real skin has several kinds, for touch, pressure, heat, cold and pain.
• The echidna's prickle stands for anything sharp: the story says "ouch" and "you pull away", and never shows a hurt. KidsHealth's own example is touching something hot.
• The lizard's line says lizards shed their skin (the Australian Museum's blue-tongue sheds its skin within days of birth), without saying how it comes off.

Where the facts come from

Every fact the tour states was checked against the page linked beside it.

• "What's the body's biggest organ? … it's the skin"; "It covers and protects everything inside your body"
  In the tour: This is your skin: your biggest organ. It covers all of you, from your head to your toes! It keeps germs out, and everything else in.
  KidsHealth (kids) — Your Skin
• The skin "protects our bodies, helps keep our bodies at just the right temperature, allows us to have the sense of touch"
  In the tour: It helps you stay cool and warm, and it lets you feel the world.
  KidsHealth (kids) — Your Skin
• "The skin is made up of three layers": the epidermis, the dermis and the subcutaneous layer
  In the tour: Here's your skin, up close. It has three layers. On top, the epidermis … Under it, the dermis … At the bottom, the fat layer.
  KidsHealth (kids) — Your Skin
• The subcutaneous layer "is made mostly of fat and helps your body stay warm and absorb shocks"
  In the tour: At the bottom, the fat layer: a cosy blanket that keeps you warm. The fat layer underneath helps keep you warm.
  KidsHealth (kids) — Your Skin
• "At the bottom of the epidermis, new skin cells are forming"; "This trip takes about 2 weeks to a month"
  In the tour: New skin cells start at the bottom of the epidermis. Up they go, getting flatter, all the way to the top. It takes about a month!
  KidsHealth (kids) — Your Skin
• "Every minute of the day we lose about 30,000 to 40,000 dead skin cells"
  In the tour: Every minute, thousands of tiny flakes of old skin fall off.
  KidsHealth (kids) — Your Skin
• "The dermis contains nerve endings, blood vessels, oil glands, and sweat glands"
  In the tour: Under it, the dermis. It's full of tiny parts that help you. (Tap: it has nerve endings, sweat glands, blood vessels and the roots of your hairs.)
  KidsHealth (kids) — Your Skin
• The dermis has "hair follicles, which produce hair all over your skin, except the palms of your hands and the soles of your feet"
  In the tour: A hair, growing from its root in the dermis.
  Cleveland Clinic — Dermis
• "sweat glands also swing into action by making lots of sweat to release body heat"; "The sweat comes up through pores, tiny holes in the skin"
  In the tour: Phew, it's a hot day! Your sweat glands start making sweat. Out it comes, through tiny holes called pores. As it dries, it takes the heat away.
  KidsHealth (kids) — Your Skin
• "special tiny muscles … pull on your hairs so they stand up very straight"; "the fancy name for them is the pilomotor reflex"
  In the tour: Brrr, it's cold! Tiny muscles pull your hairs up straight. The skin bumps up around them: goosebumps!
  KidsHealth (kids) — Your Skin
• Nerve endings let you feel "pressure, pain, heat, cold and itchiness"
  In the tour: Nerve endings: tiny feelers in your skin. They feel soft and hard, hot and cold, itchy and ouch.
  Cleveland Clinic — Dermis
• Touching something hot, "the nerve endings in your dermis respond right away"; "The nerves quickly send this message to the brain or spinal cord, which then immediately commands the muscles to take your hand away"
  In the tour: Echidna's prickle: ouch! A quick message, and you pull away.
  KidsHealth (kids) — Your Skin
• "The nerve endings in your dermis tell you how things feel when you touch them"
  In the tour: A feather: tickle! Off goes a message, along a nerve.
  KidsHealth (kids) — Your Skin
• The spinal cord is a long bundle of nerves inside the spinal column; messages flow back and forth between the brain and the body
  In the tour: Messages zip up your arm and your spinal cord, all the way to your brain.
  KidsHealth (kids) — Your Brain & Nervous System
• Fingerprint ridges "begin to develop during the third month of fetal development"
  In the tour: They grew before you were born.
  MedlinePlus Genetics — Are fingerprints determined by genetics?
• "Each person's fingerprints are unique"; "Even identical twins … have different fingerprints"
  In the tour: Nobody else has fingerprints like yours. Not even a twin!
  MedlinePlus Genetics — Are fingerprints determined by genetics?
• "the basic whorl, arch, and loop patterns"
  In the tour: (The sheet to print: loops, whorls and arches.)
  MedlinePlus Genetics — Are fingerprints determined by genetics?
• "Platelets stick together like glue to make a clot"; "As the clot gets hard and dries out, it is called a scab"
  In the tour: Platelets in your blood come to help. They stick together, like glue. They dry into a scab.
  KidsHealth (kids) — What Are Scabs?
• A scab's job is "keeping germs and other stuff out and giving the skin cells underneath a chance to heal"
  In the tour: It keeps germs out while new skin grows underneath.
  KidsHealth (kids) — What Are Scabs?
• "If you pick or pull at the scab, you can undo the repair"; "a scab falls off and reveals new skin underneath … after a week or two"
  In the tour: Don't pick it! After a week or two, it falls off by itself.
  KidsHealth (kids) — What Are Scabs?
• "Melanin gives skin its color. The darker your skin is, the more melanin you have"; skin can "make extra melanin to protect you from getting burned"
  In the tour: Melanin gives your skin its colour. The more melanin, the darker the skin.
  KidsHealth (kids) — Your Skin
• Slip on clothing, slop on sunscreen, slap on a hat, seek shade, slide on sunglasses, "when UV index is 3 or above"
  In the tour: Every skin needs looking after in the sun. Slip on a shirt, slop on sunscreen, slap on a hat, seek shade, and slide on sunglasses!
  Cancer Council Australia — Five SunSmart steps
• Lizards "do not produce their own body heat"; they "bask in sunny areas"
  In the tour: I can't make my own heat, so I find a sunny spot!
  Australian Museum — Eastern Blue-tongue Lizard
• Young blue-tongues "shed their skin for the first time" within a few days of birth (lizards shed their skin)
  In the tour: Lizards like me shed our old skin too!
  Australian Museum — Eastern Blue-tongue Lizard

Every word it says

The whole script, for reading along, or for a child who'd rather read than listen.

1. Wrapped up!

• Hello! I'm Lizard. I love a warm, sunny rock!
• This is your skin: your biggest organ. It covers all of you, from your head to your toes!
• It keeps germs out, and everything else in.
• It helps you stay cool and warm, and it lets you feel the world.
• Let's look really closely, at a tiny patch of it.

2. Three layers

• Here's your skin, up close. It has three layers.
• On top, the epidermis: the part you can see and touch.
• Under it, the dermis. It's full of tiny parts that help you.
• At the bottom, the fat layer: a cosy blanket that keeps you warm.

3. New skin

• New skin cells start at the bottom of the epidermis.
• Up they go, getting flatter, all the way to the top. It takes about a month!
• Every minute, thousands of tiny flakes of old skin fall off.
• Lizards like me shed our old skin too!

4. Hot day!

• Phew, it's a hot day! Your sweat glands start making sweat.
• Out it comes, through tiny holes called pores.
• As it dries, it takes the heat away. Ahh, cooler!

5. Brrr, cold!

• Brrr, it's cold! Tiny muscles pull your hairs up straight.
• The skin bumps up around them: goosebumps!
• The fat layer underneath helps keep you warm.
• I can't make my own heat, so I find a sunny spot!

6. Tickle, prickle

• Nerve endings: tiny feelers in your skin. They feel soft and hard, hot and cold, itchy and ouch.
• A feather: tickle! Off goes a message, along a nerve.
• Echidna's prickle: ouch! A quick message, and you pull away.
• Messages zip up your arm and your spinal cord, all the way to your brain.

7. Only you

• Look at your fingertips. Swirly ridges: fingerprints!
• They grew before you were born.
• Nobody else has fingerprints like yours. Not even a twin!

8. A graze heals

• Oops, a little graze on your knee!
• Platelets in your blood come to help. They stick together, like glue.
• They dry into a scab. It keeps germs out while new skin grows underneath.
• Don't pick it! After a week or two, it falls off by itself.

9. Look after your skin

• Melanin gives your skin its colour. The more melanin, the darker the skin.
• Every skin needs looking after in the sun.
• Slip on a shirt, slop on sunscreen, slap on a hat, seek shade, and slide on sunglasses!
• Thanks for tickling and prickling with me. Welcome to the Tickle-Prickle Club!

The quiz

Quiz time! Let's see what you remember. The right answers are in bold.

1. What's your biggest organ? (Your heart / Your skin / Your brain)
2. What comes out of your pores on a hot day? (Sweat / Milk / Sand)
3. What gives you goosebumps? (Being hungry / A sneeze / Being cold)
4. Where do new skin cells start? (At the bottom of the epidermis / On the very top / In your hair)
5. What does a scab do? (Makes you run faster / Keeps germs out while new skin grows / Nothing at all)
6. It's a sunny day. What helps your skin? (A scarf / Earmuffs / A hat, a shirt and sunscreen)

What it needs, and what we collect

A recent browser on a phone, tablet or computer. The first visit downloads about 9 MB, and after that it keeps working with no signal. Nothing about your child is collected: the My mob card and the sound setting are kept on your own device. The privacy page has the whole story.

More in the series: What Makes Me, with the Lub-Dub Club, the Huff-Puff Club, the Munch-Crunch Club, the Mix-Fix Club, the Zip-Zap Club, the Drip-Drop Club and the Five-Alive Club.