Your mission
A marble is riding in an open cup. No lid. No seat belt. Your job is to drop it from high up and have it land without bouncing out.
Work through each tab in the menu. Read how it works, then show your thinking. Each tab you finish earns a badge.
Earn all five badges to unlock the build plans. Then you get to build a real lander and test it.
My badges
Teacher note
- For each pair: 1 small paper cup, 1 square of cardboard about 4 inches wide, 2 index cards, tape, scissors, a ruler, and 1 marble.
- For the class: a meter stick or tape measure for drop heights.
- This is the classic "touchdown" engineering challenge, but with a marble as the passenger, so no food is involved.
- Loose marbles on a hard floor are a slipping hazard. Have students drop into a box lid or onto a marked landing zone, and pick up strays right away.
- The build plans unlock after all five badges are earned. Progress is saved on this Chromebook only.
- The Landing lab is a simple model. Real landers will not match its numbers, but the patterns hold: legs that squish soften the stop, legs that are too springy make it hop, and tall narrow landers tip.
- Extension: students who finished the Cup Parachute lesson can add a parachute on top and compare.
What happens when it hits
Falling is the easy part. The landing is where things go wrong.
Read: the impact
When your lander falls, gravity speeds it up the whole way down. The higher the drop, the faster it is going when it reaches the floor.
Then it has to stop. The floor pushes up on the lander to stop it. That sudden push is called the impact.
A moving object has kinetic energy, the energy of motion. When the lander stops, that energy does not vanish. It has to go somewhere. It goes into bending, squishing, sound, and a little heat.
A hard floor stops a hard object almost instantly. A stop that sudden takes a huge push. That huge push is what launches a marble right out of a cup.
Try it: raise the drop
Stretch out the stop
You cannot skip the stop. But you can make it gentler.
Read: crumple zones
Think about catching a water balloon. If you hold your hands stiff, it pops. If you let your hands move back with the balloon, it stays whole.
Moving your hands gives the balloon more time and more distance to stop. Here is the rule: a longer stop needs a smaller push.
Engineers use this rule everywhere. The front of a car is built to crumple in a crash. That part is called a crumple zone. A bike helmet has foam that crushes. Gym mats and airbags do the same job.
The folded paper legs on your lander are its crumple zone. When they squish, the stop takes longer, and the push on the cup gets smaller.
But watch out. If the legs squish completely flat while the lander is still moving, the cushion is used up. Engineers call this bottoming out. The rest of the stop is sudden.
Try it: change the stopping time
Bounce or absorb?
Not everything that squishes makes a good cushion.
Read: where the energy goes
Some things bounce back when you squish them. A rubber ball does. So does a metal spring. They store the energy for a moment, then give it right back.
Other things soak the energy up. A lump of clay hits the floor and just stays there. Its energy went into changing its shape.
A lander needs legs that absorb. Legs that are too springy store the landing energy and then launch the whole lander back into the air, like a pogo stick. It hops, wobbles, and may tip over.
Folded paper is only a little springy. Each fold bends and rubs as it squishes, and that soaks up energy.
The marble can bounce too. If the cup stops suddenly, the marble keeps going, slams into the bottom of the cup, and bounces up. A big enough bounce carries it over the rim.
Big idea: Structure. A flat strip of paper is floppy. Fold that same strip and it becomes a spring. The shape of a material decides what it can do.
Try it: drop two balls
Pick a ball to drop.
Keep it on its feet
A soft landing does not help if the lander falls over.
Read: wide and low
When a lander tips, the marble spills. So a good lander has to stay upright too.
Make the base wide. The farther apart the feet are, the harder it is to tip. Real spacecraft landers have legs that spread way out to the sides for this reason.
Keep the weight low. The balance point of an object is called its center of mass. Tall, skinny legs lift the cup and the marble high above the feet, and that makes the lander wobbly.
So there is a trade. More folds give the legs more cushion. But more folds also make the legs taller. A good engineer finds the balance between soft and steady.
Try it: two designs
Wide and low. Hard to tip.
Landing lab
Design a lander, drop it, and watch the landing in slow motion. The marble has to stay in the cup.
Missions
Finish all four missions to earn the Mission Commander badge.
Design it
A jolt of 1 g is the normal push you feel from the floor when you stand still. A jolt of 50 g is 50 times that.
Push from the floor
A tall, skinny spike is a sudden stop. A low, wide hill is a gentle one. The dashed line is your last drop.
My drops
| Height | Folds | Legs | Platform | Jolt | Result |
|---|
Your drops will show up here, newest on top.
This lab is a model. A real lander will not match these numbers exactly, but the patterns are the same.
Build it
The build plans are locked
Earn every badge to open them. You still need:
You earned it. Time to build a real lander.
How to build your marble lander
You need: a small paper cup, a square of cardboard, 2 index cards, tape, scissors, a ruler, and a marble.
- Cut a square of cardboard about 4 inches wide. This is your platform.
- Tape the cup to the middle of the platform with the open side up.
- Cut each index card in half the long way. Now you have 4 strips.
- Fold each strip back and forth like a paper fan. These are your legs.
- Tape one leg under each corner of the platform.
- Put the marble in the cup. No lid, and nothing covering the top.
- Hold the lander level at knee height and let go. If the marble stays in, go higher.
Stay safe: drop over a box lid or a marked landing zone, and pick up loose marbles right away so nobody slips.
The plan
The picture shows two legs. Your lander has four, one under each corner.
Test like a scientist
Change only one thing at a time. For each design, find the highest drop where the marble stays in. Try it three times and write the height in centimeters.
| What I changed | Highest safe drop, try 1 | Try 2 | Try 3 | Average |
|---|
Ideas to test: add more folds, use fewer folds, angle the legs outward, make the platform wider, or add a parachute like the one from the Cup Parachute lesson.