Marshmallow and Toothpick Tower Challenge (Fun STEM Activity for Kids)

Can your kids build a marshmallow and toothpick tower tall enough to stand on its own? This easy marshmallow STEM challenge uses just two supplies and works for kindergarteners, elementary kids, and even middle schoolers. Here’s how we did it, plus tips to make it even more fun!

I was only going to supervise. That was the plan. Just set the kids up with some marshmallows and toothpicks and let them build while I get stuff done around the house.

Ten minutes later, I was crouched at the kitchen table, building my own marshmallow and toothpick tower and getting weirdly competitive about it.

That’s the thing about this challenge – it pulls you in. The concept is simple (build the tallest tower you can using only marshmallows and toothpicks), but the problem-solving is surprisingly deep. Why does this shape stand and that one doesn’t? What makes triangles stronger than squares? Your kids will figure these things out on their own, one wobbly tower at a time.

If you’re looking for a hands-on STEM activity that takes about two minutes to set up and keeps the whole family busy for way longer than you’d expect, this is the one.

What Is the Marshmallow and Toothpick Tower Challenge?

The concept is simple: give your kids a bag of mini marshmallows and a box of toothpicks, and challenge them to build the tallest freestanding tower they can.

That’s it. No glue. No tape. No other materials allowed.

The tower must stand on its own, without anyone holding it or leaning it against anything.

This marshmallow STEM challenge works great at home, in classrooms, at birthday parties, for scout troops, or even as a rainy-day boredom buster. It scales easily from kindergarten through middle school. The basic concept remains the same, but the designs become increasingly sophisticated as children grow older.

And it’s one of those activities where every kid’s tower looks completely different, which makes it really interesting to compare at the end.

Why Kids (and Adults) Love This Marshmallow Toothpick Challenge

There’s something about marshmallows that makes everything better, right?

But beyond the snacking potential, here’s why this activity is such a hit across ages:

• It’s open-ended. There’s no single right answer, which means a 5-year-old and a 12-year-old can both have a blast doing the exact same challenge.
• It’s hands-on. Kids learn by doing – and this challenge is all about doing.
• It teaches real engineering concepts. Are triangles stronger than squares? They’ll figure that out on their own when their square tower wobbles.
• It builds problem-solving skills. When the tower falls (and it will), kids have to figure out why and try again.
• It’s a great fine motor workout. Pinching those little marshmallows and carefully poking toothpicks into them is surprisingly good for hand strength and coordination, especially for younger builders.
• It’s fun for adults, too. I’m not kidding. If you’re a parent or teacher, give yourself a pile of marshmallows and try to beat your kids’ tower height. Prepare to be humbled.

The best part is watching the look on their face when their tower actually stands up. Pure pride – no matter what age they are.

What You Need

Here’s your very short supply list:

• Mini marshmallows
• Toothpicks
• A flat surface to build on
• A ruler or measuring tape (for measuring the final tower)
• A timer (optional, but adds excitement!)

Tip: Slightly stale marshmallows actually work better! If yours are super fresh and squishy, leave the bag open for an hour or two before you start. Firm marshmallows hold toothpicks better and make sturdier towers.

How to Do the Marshmallow and Toothpick Tower Challenge

Step 1: Warm Up with Shapes

Before jumping straight into tower-building, let your kids play around with the materials for a few minutes. Have them build simple 2D shapes first (triangles, squares, pentagons, etc.).

This helps them understand how the marshmallows and toothpicks connect. For younger kids, it’s also a chance to practice that pinching motion. My daughter squished most of her marshmallows and made a sticky mess before figuring out you shouldn’t slide the marshmallows down the toothpicks.

Then take it up a notch: can they turn a 2D triangle into a 3D pyramid? A flat square into a cube?

This is where you’ll start to see the lightbulbs go off. They’re not just building – they’re discovering geometry without even realizing it. Older students and middle schoolers can explore more complex shapes, such as octahedra or hexagonal prisms.

If your kids love building shapes, check out our marshmallow and toothpick geometry activity!

Step 2: Plan the Design

Before they start building, give your kids a minute to think about their tower design. You can even have them sketch it out on a piece of paper first.

Ask them a couple of guiding questions:

• What shape do you think would make a strong base?
• Should the base be wide or narrow?
• How will you connect the shapes to build upward?

For younger kids (ages 5–6), they might skip the planning and jump right in. That’s totally fine! They’ll learn through trial and error, which is a great way to learn.

Elementary kids (ages 7–8) tend to get more strategic, and you might see some impressive blueprints.

Middle schoolers? Give them graph paper and watch them go full architect mode. You can even have them calculate how many marshmallows they’ll need for their design before they start building.

Step 3: Set the Rules

Keep the rules simple:

• You can only use marshmallows and toothpicks. No tape, no glue, no leaning against anything.
• The tower must be freestanding and stand on its own for at least 10 seconds to count.
• Set a time limit. We started off with 15 minutes, and trust me, time passed in the blink of an eye. We ended up using 20 minutes. Younger children may need a little more time, while older children and middle schoolers can handle tighter time constraints.

You can also set a material limit to add an extra layer of challenge. Try giving each person exactly 30 marshmallows and 40 toothpicks and see what they come up with!

Step 4: Build!

This is the fun part. Set the timer and let them go.

As they build, resist the urge to jump in and help (I know, it’s hard). Instead, ask questions:

• “Why do you think that side is leaning?”
• “What could you add to make it more stable?”
• “What if you tried a triangle shape there instead?”

When their marshmallow and toothpick tower inevitably wobbles or collapses, just let it happen! They’ll problem-solve, adjust their design, and try again.

This is the engineering design process in action: plan, build, test, improve. And they’re doing it with marshmallows.

Fair warning: if you start building your own tower alongside them, things might get competitive. In our house, the kids spent just as much time trying to beat my tower as they did building their own.

That said, here is mine, mid-construction, about to fall over.

Step 5: Measure and Reflect

When time’s up, measure each tower from the base to the highest point.

Then talk about it:

• What worked well in your design?
• What would you do differently next time?
• Which shapes seemed the strongest?
• Did a wide base or a narrow base work better?

For older kids, you can push the reflection further: What forces were acting on the tower? Why did certain designs fail? How is this similar to how real engineers design buildings?

If your kids are up for it, let them try again! The second round is almost always taller because they learned so much from the first attempt.

Tips for Building the Tallest Marshmallow and Toothpick Tower

After doing this challenge with my kids – and failing spectacularly on my own tower before figuring a few things out – here’s what we learned:

Start with a wide, sturdy base. This was the number one factor. The towers with large, solid bases always performed better than those that started skinny. Think wide triangles or squares at the bottom.

Use triangles for strength. Triangles are the strongest shape in engineering because they distribute weight evenly and don’t collapse easily. If your tower keeps wobbling, add diagonal toothpicks to form triangles.

Go light at the top. The most common mistake? Making the top just as heavy as the bottom. The higher you go, the lighter and simpler the structure should be.

Don’t squish the marshmallows too much. Over-handled marshmallows get warm and sticky and won’t hold the toothpicks well. Gentle hands are key.

Build symmetrically. Lopsided towers tip over. Build evenly on all sides as you go up.

Break toothpicks for shorter supports. This is a trick the older kids figured out. Sometimes you need a shorter connection, and snapping a toothpick in half gives you greater flexibility in building.

But watch out for splinters! I didn’t let my kids do this to keep things simple, but they definitely asked. I was also curious about what they could do using only full-length toothpicks.

How to Adapt the Challenge by Age

One of the best things about this marshmallow toothpick challenge is how it works across a huge age range. You just tweak the expectations.

Kindergarten and Early Elementary (Ages 5–6)

At this age, focus on the fun of building and exploring. Don’t worry too much about height. These kids are developing fine motor skills just by connecting marshmallows and toothpicks.

Keep the time limit generous (25–30 minutes) and celebrate any structure that stands on its own. If they want to build a “house” or “robot” instead of a tower, let them! The engineering concepts are the same.

Upper Elementary (Ages 7–8)

This is the sweet spot for the classic tower challenge. These kids can plan, build strategically, and reflect on what worked.

Add a material limit (like 50 marshmallows and 50 toothpicks) and a 20-minute timer to make it more exciting. Encourage them to sketch a design before building.

Middle School (Ages 10–13)

Crank up the challenge. Give middle schoolers tighter material constraints, shorter time limits, or additional requirements like “your tower must support a tennis ball at the top.”

You can also have them research real-world structures beforehand and apply what they learn. Why are skyscrapers narrower at the top? How do bridges distribute weight? This turns the marshmallow tower into a full engineering lesson.

Pair them in teams and add a competition element. Middle schoolers thrive on friendly competition, and you’ll see some seriously creative designs.

Adults (Yes, Really)

I wasn’t planning on building a tower. But then my kids challenged me and… well, I couldn’t say no.

It turns out this is a genuinely fun challenge for adults, too. It’s a great family bonding activity where everyone’s on the same playing field. And let me tell you, there’s nothing quite like the humbling experience of watching your tower fall and your 9-year-old’s tower twice as tall as yours.

And of course, I couldn’t just let it go. I redesigned and beat my kids at the end! Victory!

The Science Behind the Marshmallow Tower Challenge

This isn’t just a fun activity – there’s real science and engineering happening here.

When kids build a marshmallow and toothpick tower, they’re working with two main forces:

• Compression – the downward force of gravity pushing on the marshmallows and toothpicks.
• Tension – the pulling force that tries to stretch or pull apart the connections.

They’re also learning that certain shapes handle these forces better than others. Triangles, for example, are incredibly stable because they can’t be deformed without changing the length of one of their sides. That’s why you see triangles in bridges, roof trusses, and construction cranes.

Squares and rectangles, on the other hand, can shift into parallelograms under pressure. That’s why a square-based tower wobbles, unless you add diagonal supports (which create… triangles!).

For younger kids, you can keep the science talk simple: “Triangles are strong shapes. Squares can wobble.” For middle schoolers, you can introduce terms such as compression, tension, load distribution, and structural integrity.

You don’t need to turn this into a full science lecture. But if someone asks, “Why does my tower keep falling?” – now you’ve got a great answer.

Fun Variations to Try

Once your kids have mastered the basic tower challenge, mix things up with these variations:

The 30 Marshmallow Challenge: Give each person exactly 30 marshmallows and see who can build the tallest tower. The limit forces everyone to be strategic about every single piece. This is what we did!

Earthquake Test: After the towers are built, place them on a cookie sheet and gently shake it. Whose tower can survive the “earthquake”? This is a great tie-in to earth science concepts.

Weight-Bearing Challenge: Instead of the tallest tower, challenge kids to build the strongest one. Can their tower hold a small book on top? A tennis ball? Keep adding weight to see who built the sturdiest structure.

Replicate a Famous Structure: Pull up a picture of the Eiffel Tower, a pyramid, or a skyscraper and see if your kids can recreate it. This one’s especially great for middle schoolers, as it sneaks in history, architecture, and geography all at once.

Family Tower-Off: Everyone builds their own tower – parents included. The loser does the dishes (just kidding… kind of).

Love marshmallow STEM challenges? Try our tallest marshmallow snowman challenge for a fun winter twist!

Marshmallow and Toothpick Tower FAQ

What age is this activity best for?

This marshmallow toothpick challenge is most popular with kids ages 5–8, but it works really well for a much wider range. Younger kids (ages 3–4) can participate with some help; middle schoolers love the competitive challenge; and adults genuinely enjoy it, too. It’s one of those rare activities that scales up or down with almost no changes.

Can I use regular-sized marshmallows instead of mini?

You can, but mini marshmallows work much better for this activity. They’re lighter, easier to connect with toothpicks, and let kids build taller towers without the structure getting too heavy.

What if my kids just eat the marshmallows?

Ha – been there! Set aside a separate snack bowl of marshmallows for eating. Let them know that building marshmallows is off-limits until the challenge is complete. (Some parents even set out “stale” ones for building and fresh ones for snacking.)

How tall should a marshmallow tower be?

It depends on your builders’ age and experience. For first-timers ages 5–6, anything over 6–8 inches is a great start. Elementary kids with a little guidance can often reach 12–18 inches. Middle schoolers working in teams may be able to hit 2 feet or more! But the real goal is the process, not the measurement.

Can I use this activity in a classroom?

Absolutely! This is one of the most popular STEM classroom challenges for students from kindergarten through middle school. Divide students into teams of 2–4, set the timer, and let them compete. It’s great for teamwork, communication, and collaborative problem-solving.

What can I use instead of marshmallows?

If marshmallows aren’t an option (allergies, diet restrictions, etc.), you can try gumdrops, jelly beans, Play-Doh balls, or even small pieces of modeling clay. Each material creates a slightly different challenge!

For a Valentine’s Day version, check out our heart jelly bean and toothpick structures STEM activity.

Is this good for a science fair?

It can be! A great science fair angle would be testing which base shape (triangle, square, pentagon) produces the tallest stable tower. Kids can run multiple trials, measure results, and draw conclusions – all the elements of the scientific method.

Final Thoughts on Marshmallow and Toothpick Tower STEM Challenge

The marshmallow and toothpick tower challenge is simple to set up, works for ages 5 through middle school (and beyond), and sneaks in real engineering concepts while everyone’s having too much fun to notice.

So grab a bag of mini marshmallows and a box of toothpicks. Set a timer. And see what your little (or not so little) engineers can build!

More STEM Challenges Your Kids Will Love:

• Ultimate Egg Drop Challenge Guide
• Simple DIY Marshmallow Catapult
• Free Printable 30-Day LEGO STEM Challenge Calendar
• Candy Cane Bridge STEM Challenge
• Marshmallow and Toothpick STEM Activities