A cardboard robot hand is a simple mechanical model that lets children investigate joints and pulling forces. It is operated by string, not a motor, computer or hydraulic system. Start with one moving finger before making a whole hand. That keeps the first test manageable and makes it easier to see which part needs adjusting.

Cardboard Robot Hand: What You Will Learn

The model uses flexible folds as joints and strings as pull-cords. Pulling a cord on the palm side can bend a finger towards that side. This offers a simplified analogy for a tendon-driven mechanism, but it does not reproduce the full structure or movement of a human hand.

Expect to test and revise the placement of guides and folds. The instructions describe a design starting point, not a claim that every combination of card, tape and string will work immediately. A successful first result is one finger bending and being reset reliably.

Materials and Safety

• Thin card, such as a clean cereal box with sharp or damaged edges removed.
• A pencil, ruler and age-appropriate scissors.
• Paper drinking straws or short rolled-paper guide tubes.
• Short lengths of string and masking tape.
• A lightweight paper object for a later grasping test.

An adult should help with cutting and check the materials. Keep loose string and small pieces away from young children. Do not tie cords around fingers, wrists or the neck. Avoid needles, hot glue, sharp wire and elastic launch mechanisms. Do not use the model to pinch skin or pick up fragile, hot or heavy objects.

Step 1: Make One Test Finger

Cut a narrow strip of thin card with enough length for three finger sections and a small base section. Draw two fold lines across the moving part, leaving space between them. Fold gently so the strip can curl towards one side without tearing.

Mark that side “palm”. Bend the card by hand first. If it is too stiff to fold smoothly or splits at the joint, try thinner card or a wider strip before adding a cord. The material needs to move reliably before the mechanism can help.

Step 2: Add Cord Guides

Cut short straw sections and tape one along each finger segment on the palm side. Leave a gap at every fold so a straw does not bridge and lock the joint. Align the guides so a string can pass through them without catching.

The guides should be firmly attached without being flattened shut. Pull a spare piece of string through the path before fixing its end. If it jams, adjust the guide rather than pulling harder.

Step 3: Attach and Route the String

Secure one end of the string near the fingertip on the palm side with a folded tape tab. Run the free end through the guides towards the base. Leave a short tail that can be held comfortably without wrapping it around the hand.

Hold the card’s base still and pull the string gently. The finger should begin to curl towards the cord side. Release the pull and straighten the finger by hand. This beginner model does not include an automatic return mechanism, and it should not be described as doing so.

Step 4: Troubleshoot Before Expanding

The finger stays straight: check that the folds are flexible, the string is secured at the tip and the guides do not cover the joints. Try a small change in guide placement.

The whole strip moves: stabilise the base against the table with your other hand. A loose base can hide whether the finger mechanism is working.

The tape peels: reduce the pulling force and improve the attachment area. A mechanism that needs excessive force is a reason to redesign, not to pull harder.

The cord catches: check alignment and make sure tape has not blocked a guide opening. Test the cord path independently before repeating the full movement.

Step 5: Build a Hand Shape

Once the test finger works, draw a large hand-like outline on thin card with separated fingers and a broad palm. You do not need anatomically exact proportions. Give each finger enough width for its folds and guides.

Add the same mechanism to one finger at a time. Label the pull-cords so the learner can identify which finger each controls. Keep the thumb simple or fixed for the first version rather than claiming a full opposable-thumb movement.

Try curling the fingers around a very light crumpled-paper object. Hold the palm steady and observe whether the object slips. This is a design test, not a lifting-strength competition.

Explain the Mechanism

Ask where the pulling force enters the model and where the finger bends. Discuss why the string can pull but does not push the finger straight again. Identify the manual reset as a limitation.

For a different design approach, see the Science Buddies robot-hand activity. Its materials and mechanism differ, so follow that resource’s own instructions if you choose it. Do not combine unfamiliar components without reviewing the resulting design.

Test One Improvement

Change one feature, such as the distance between guides or the card thickness, and compare three gentle pulls. Record whether the motion is smoother and whether the cord or tape slips. Do not invent a success rate from a single attempt.

Finish with a labelled sketch showing the base, joints, guides and cord. Explore our Robotics hub and Engineering hub to connect this mechanical model with later controlled systems.

A DIY solar system model can teach planet order, relative size or distance, but a small tabletop display usually cannot show all three accurately at the same scale. Decide what your model is intended to explain before choosing materials. This project offers two complementary versions: a labelled display for identifying planets and a distance model that reveals how much space lies between them.

DIY Solar System Model: Choose What Is to Scale

Our solar system includes the Sun and eight planets, along with many other bodies. For this introductory model, use Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Explain that leaving out moons, dwarf planets and smaller bodies makes the model simpler, not complete.

NASA JPL’s scale-model project distinguishes modelling planet sizes, distances or both. Its Solar System Scroll activity also addresses the misleading impression that planets are evenly spaced. Use these resources to check your chosen scale and learning goal.

Version One: A Labelled Tabletop Display

Materials: card, paper circles or suitable craft balls, colouring materials, glue appropriate for the children present and paper labels. Use large pieces where small objects would be a choking risk. An adult should handle difficult cutting. Avoid sharp skewers and hot glue in a beginner activity.

1. Make a large label for the Sun and one label for each planet.
2. Choose clearly distinguishable shapes or colours, using NASA references rather than assuming every artistic colour is a literal view.
3. Place the planets in order from the Sun.
4. Add a visible note: “Planet sizes and distances are not shown to the same scale.”
5. Ask the child to explain what the display shows accurately and what it simplifies.

Jupiter should be represented as larger than Earth if you are illustrating relative size informally, but do not call the display an exact size model unless you calculate and measure the dimensions. Attractive spacing is not evidence of accurate distance.

Version Two: A Distance Model

For an illustrative outdoor model, use a scale of one metre representing roughly one hundred million kilometres. The rounded distances below are measured from the Sun, not from the preceding planet. They represent approximate orbital distances, not fixed positions of planets that remain in a straight line.

Check the values and scale with the NASA resource before using them for a formal school assignment. The rounded figures are sufficient to discuss spacing, not to predict where a planet is today.

Set Up the Distance Walk Safely

Choose an approved level area away from traffic, water hazards and restricted spaces. An adult should assess weather, access and supervision. Never look directly at the Sun during an astronomy activity. Use a labelled card on the ground as the model Sun.

Measure every position from that starting point and place a large planet label at each distance. Keep labels clear of walkways and avoid string stretched where people could trip. If you do not have approximately forty-five metres of safe space, choose a smaller scale or use a paper-strip activity.

Ask children to predict where the outer planets will go before measuring. Compare their predictions with the model and discuss why many familiar illustrations compress the empty space.

Why the Planets Become Tiny at This Scale

At the distance scale above, Earth’s diameter would be about 0.13 millimetres and the Sun’s about 14 millimetres. Large craft balls placed along the walk therefore represent location markers, not correctly scaled planet sizes. State that explicitly.

This is the central learning point: a model can make one relationship easier to see while distorting another. A tabletop display and a distance walk can both be useful when their limitations are labelled honestly.

Questions for Different Learners

For younger learners: ask which planet comes next, which group lies closer together and which gaps surprised them. Let them draw or dictate an observation.

For older learners: ask how the positions change if one metre represents twice as much real distance. All model distances halve. Ask why doubling the size of only Earth would break a consistent scale.

Another extension is to compare a distance model with a size-only model. Keep the two labelled separately so a learner does not mistake the combined display for one consistent physical representation.

Keep the measurement record with the finished display. If another group rebuilds it using your instructions, they should know the starting point, the unit and the rounding used. Clear documentation makes the model easier to check and improve.

Finish with a Model Explanation

Ask the child to complete three sentences: “Our model shows ___ accurately. It simplifies ___. We chose this scale because ___.” That explanation is more valuable than a perfectly painted set of balls with no account of scale.

Explore our Science hub for further explanations and our STEM projects hub for practical investigations.

Kitchen science experiments can help children investigate mixtures, materials and change with everyday supplies. The kitchen is also a food-preparation space, so separate the experiment from eating, check allergies and clean up afterwards. These seven activities avoid open flames, heating paper, raw-egg handling and borax-based slime. An adult should still choose and supervise each activity for the children present.

Kitchen Science Experiments: Safety and Setup

Use small quantities on a washable tray. Do not taste materials, even when they began as food. Keep liquids away from sockets and devices, wash hands, and label experiment containers so nobody mistakes them for a drink. Adults should manage any cutting and check household products before use.

Choose one question per activity. “What happens?” is a good start, but a comparison becomes more useful when you change one factor and keep the others consistent. These are adaptable teaching ideas, not guaranteed outcomes or evidence that a particular product is best.

1. Cornflour Oobleck

You need: cornflour, also called cornstarch, water, a bowl and a spoon. Begin with roughly two parts cornflour to one part water by volume, adding water gradually until the mixture is workable. Keep dry powder away from faces and avoid creating dust.

Press the mixture quickly with the spoon, then move the spoon slowly. Compare how it resists the two motions. This suspension can behave differently under different stresses; it is not simply turning permanently from a liquid into a solid.

The Science Buddies oobleck activity provides further explanation. Collect the mixture for disposal in household rubbish where local rules permit, rather than pouring a thick batch down the sink. Do not store it as food.

2. Oil and Water Layers

You need: a clear unbreakable container, water, a small amount of cooking oil and a tray. Pour the water first, then add oil. Observe the layers without tasting or touching the mixture unnecessarily.

Stir gently with a spoon and watch what happens after it rests. Oil and water do not mix readily, and the cooking oil usually forms the upper layer because it is less dense than water. Do not add rubbing alcohol, unknown cleaners or other household chemicals.

Ask the child to draw the container immediately after stirring and again later. The comparison separates a temporary dispersion from a lasting mixture. Wipe up the oil and dispose of it appropriately rather than pouring it down the drain.

3. Colour on a Paper Towel

You need: white paper towel, washable water-based markers, a shallow container and water. Draw a small mark near one end of a strip. Place only the very bottom edge in water, keeping the ink mark above the starting water level.

Watch the water travel through the paper. Some marker inks separate into different colours as their components move differently. Not every pen will separate clearly, so a single unchanged colour is still an observation rather than a failed lesson.

Compare two pens using equal strips and the same water depth. Keep the experiment materials away from food and clean any stains promptly. No iron, lamp or flame is needed.

4. An Open-Cup Fizz

You need: a small open cup, a tray, a little baking soda and household vinegar. An adult sets out small quantities. Add a small spoonful of baking soda to the cup and slowly add a little vinegar while keeping faces away.

The reaction releases carbon dioxide gas, visible as bubbles. Keep the container open: never seal the mixture in a bottle or use it to launch a projectile. Do not add cleaners or taste the mixture.

For a comparison, vary only one measured ingredient and keep the other conditions consistent. A larger overflow is not automatically a better experiment. Record the method as carefully as the visible result.

5. Dissolving Sugar

You need: two clear cups, equal amounts of room-temperature water, equal small amounts of sugar and a spoon. Stir one cup at a steady rate while leaving the other still.

Observe how quickly visible grains disappear. Stirring can affect the rate of dissolving; it does not necessarily change the final amount that can dissolve at that temperature. Keep the sugar quantity small enough for a manageable comparison.

Do not call the sugar “gone”. Discuss how it can remain in the water even when individual grains are no longer visible. Discard the experimental mixture rather than serving it as a drink.

6. Ice-Melting Observation

You need: two similar ice cubes, two small dishes and a timer. Place one dish in a warmer room location and one in a cooler location chosen by an adult. Avoid appliances, heaters and direct contact with electrical equipment.

Record the starting conditions and observe the melt over time. The cubes should begin as similar as possible. Ask what else might differ, such as airflow or the surface beneath the dish. This helps children recognise limitations rather than claiming a perfect controlled test.

7. Folded Paper and Water Spread

You need: equal-sized pieces of paper towel, a dropper, water and a tray. Fold one sample and leave another flat. Add the same small number of drops to each, using the same pace and position.

Compare where the water spreads and how the layers feel afterwards. State the question narrowly: you are observing a particular arrangement, not proving which paper towel is universally most absorbent. Repeat with fresh dry samples if the first result is unclear.

Keep a Small Science Record

For each activity, record the question, materials, change made and observations. Let children draw or dictate instead of requiring a long written report. Ask what evidence would make them change their explanation.

Explore our Science hub for explanations and our STEM projects hub for further supervised investigations.

STEM activities at home do not need an expensive kit. A useful activity gives a child something to predict, build, measure or explain using materials you can supervise safely. These ten ideas cover science, technology, engineering and maths. Choose one, keep the first version simple and leave time to talk about what happened.

STEM Activities at Home: Prepare First

Use clean materials, a stable work surface and suitable adult supervision. Check allergies and keep small parts away from children who may mouth them. Adults should handle difficult cutting. Keep water away from electrical equipment, avoid mains-powered experiments and do not taste experiment materials.

The suggested times describe a short exploration, not guaranteed completion times. Some observations take longer. For a broader selection of activities, see the Science Buddies STEM collection. The ideas below are practical starting points to adapt to your child, not reports of tests conducted by BrainyBloomClub.

1. Fold a Paper Bridge

Materials: paper, two equal-height books, a few suitable counters and a tray. Time: about twenty minutes.

Set a short gap between the books on a stable table. Compare a flat sheet with an equal-sized accordion-folded sheet. An adult adds the same small load to each, stopping at visible sagging. Never use body weight or heavy objects. Ask how changing the shape affected bending.

2. Build a Freestanding Tower

Materials: paper, tape and a ruler. Time: about twenty minutes.

Use a fixed amount of paper and tape to build a tower that stands without support. Measure from the table to its highest point. Compare a broad base with a narrow base while keeping the material allowance similar. Keep structures low enough to handle without climbing or reaching overhead.

3. Explore Floating Foil

Materials: a shallow water tray, foil and a few suitable counters. Time: about fifteen minutes.

Shape foil into a small boat and predict whether it will float. Try changing the sides or widening the base. Add only a small supervised load and record what happens. Keep the water shallow, clean spills promptly and stay with the child. Discuss how the boat’s shape affects the water it displaces.

4. Make a Paper Helicopter

Materials: paper and age-appropriate scissors. Time: about twenty minutes.

Make a simple paper rotor with two blades folded in opposite directions. Release it from an adult’s hand at a modest fixed height over a clear floor area. Do not climb onto furniture. Compare two blade lengths using the same paper and release height, and note whether the motion changes consistently.

5. Send Instructions to a Paper Robot

Materials: a drawn grid, a paper character and instruction cards. Time: about fifteen minutes.

One person writes “move one square right” or “turn left”; the other follows the instructions exactly. Keep the activity on the table. Introduce one ambiguous instruction and improve it together. This explores algorithms and debugging without a device or a blindfolded obstacle course.

6. Sort and Explain

Materials: large safe household objects or picture cards. Time: about ten minutes.

Sort by one visible property, such as shape, then sort the same collection by a different property. Ask the child to explain the rule and place a new item. A useful extension is to find an object that belongs in two groups and discuss why categories can overlap.

7. Measure a Shadow

Materials: paper, a pencil and a stationary object in a safe location. Time: a few minutes at several points in the day.

Mark the object’s shadow and record the time. Return later without moving the object and compare direction and length. Never look directly at the Sun. This is a repeated observation, not a thirty-minute experiment, and clouds may affect what you can see.

8. Compare Paper Absorption

Materials: equal-sized paper samples, water, a dropper and a tray. Time: about twenty minutes.

Add the same number of drops to each sample and observe the spread. Keep sample size, water and timing consistent. Repeat with fresh dry samples. Ask what the test measures and what it does not: the largest wet patch is not automatically proof of the greatest total absorbency.

9. Create a Pattern Rule

Materials: coloured paper shapes. Time: about ten minutes.

Arrange a repeating sequence such as circle, square, square. Ask the child to continue it, explain the repeating unit and make a different sequence using the same rule. Older learners can predict a later position and explain their reasoning rather than counting every shape.

10. Design Packaging for a Paper Ball

Materials: scrap paper, a small cardboard box and tape. Time: about twenty minutes.

Challenge the child to keep a paper ball from moving much inside the box. Gently tilt the closed box rather than dropping it from a height. Compare two packing arrangements using the same amount of material. The goal is a justified design choice, not protecting a raw egg through increasingly risky drops.

Turn Activity into Learning

Finish with three questions: What did you predict? What did you notice? What would you change next time? Younger children can draw their answer; older learners can record measurements and compare repeats. Keep surprising results rather than forcing the expected answer.

Find more on our STEM projects hub and use our Parents hub to plan a manageable learning routine.