Bean Seed in a Cup: Watch Roots and Shoots Grow

A dry bean is a seed with a tiny plant waiting inside. Tucked against wet paper towel in a clear cup, it lets children see what normally happens underground: the seed coat splits, a root pushes down, and a shoot climbs toward the light. Setup takes about 20 minutes; observing takes 5 minutes a day for one to two weeks.

Safety: these sprouts are not food. Raw sprouts (including bean sprouts) are on the FDA’s list of foods that people at higher risk of foodborne illness should avoid, and the FDA says children younger than 5 have a high risk. Sprouts grown in a warm, damp cup at school or home should never be eaten, by children or adults. The beans are not for eating either, dry or soaked: they are for looking only. Whole beans are on the CDC’s list of choking hazards for young children. Adults keep dry and soaked beans away from children under 4 (including younger siblings), and with under-5s the adult holds the beans while children look. Keep beans away from mouths and noses, and count them in and out.

What children learn

• Seeds such as beans, peas, lentils and sunflower seeds are a plant part people eat. A bean holds a baby plant and stored food for it.
• Roots usually grow down and shoots grow up, even if you turn the cup.
• How to observe, measure and record changes over time.

You’ll need

• Clear cups, paper towels and dry beans from the bulk bin or a bag. Pinto, lima and black beans are large and easy to see. Skip red kidney beans for this activity. Use 3–4 beans per cup, since not every bean will sprout. Some store beans are old and may not sprout at all, so a few extra cups help.
• A ruler, tape for names, and the Bean Seed Observation Journal.

Before you start (prep, the night before)

1. Rinse the beans and soak them in a bowl of water overnight. Soaking is optional but speeds things up. Keep the soaking bowl out of reach of young children.
2. Clear a spot that is warm, not in direct hot sun, and away from food-prep areas.
3. Plan for handwashing. Everyone washes hands with soap and water after touching beans, wet paper towels or cups, especially before eating.
4. Check allergies. Ask families about food allergies, including allergies to beans, peas, soy or peanuts (peanuts are legumes too). Peanuts and soybeans are among the nine major food allergens in the U.S. Children with these allergies can be the recorder or measurer, or wear gloves, and families with questions should talk with their child’s doctor or allergist.

Steps: setup day (about 20 minutes)

1. Predict (3 minutes). Show a soaked bean and a dry one. Children 5 and older can pass them around; with under-5s, the adult holds the beans and children look (don’t pass loose beans around). “What changed? What do you think is inside?” Older children can gently split one soaked bean open with their fingers to find the tiny leaves and root tip inside. Throw that bean away afterward.
2. Line the cup (5 minutes). Fold a paper towel and press it around the inside wall of the cup. Stuff a second crumpled towel in the middle so the first one stays pressed against the plastic.
3. Place the beans (3 minutes). Slide 3–4 beans between the towel and the cup wall, about halfway down, so they’re visible from outside. Space them apart.
4. Water (2 minutes). Pour in a little water so the towel is damp all the way up, with only a small puddle (about 1 cm or ½ inch) at the bottom. The beans should touch damp towel, not sit in water.
5. Label and record (5 minutes). Put names on the tape. Fill in Day 0 in the journal: draw the bean and write a prediction (“I think a root will come out in ___ days”).
6. Wash hands (2 minutes).

Daily check (5 minutes a day)

• Check that the towel is still damp. Add a splash of water if it feels dry.
• Measure the longest root and the longest shoot. Record in centimeters (older children) or “longer than / shorter than a paper clip” (younger children).
• Draw what you see and add one word: split, root, hair, hook, leaf, green.
• In a school, start on a Monday, add a little extra water on Friday, or send one cup home with an adult over the weekend. It’s fine to leave weekend rows blank.

What you’ll probably see. Timing varies with temperature and the kind of bean, so treat this as a rough guide. Often within a few days the seed coat splits and a white root appears. Fine root hairs may follow. A curved shoot usually emerges next, then straightens and opens its first leaves, often within about a week to two weeks (Penn State Extension says to expect sprouts within about a week, depending on the seed). Some beans never sprout. That’s a normal result and worth discussing.

Mold: what to do

Warm, wet cups can grow mold: fuzzy white, gray, green or black spots on the beans or towel. It’s common and it’s not a failure.

• An adult removes moldy beans or the whole cup, seals it in a bag and throws it away. Wash the area and your hands.
• Children with mold allergies or asthma should not handle moldy cups. If you have concerns, talk with the child’s family.
• To reduce mold: don’t overwater, keep only a shallow puddle, give the cup some air, and replace the paper towel if it smells sour.

What happens next

When the shoot has leaves, the plant has used much of the bean’s stored food. You can transplant seedlings into small pots of soil with the root pointing down, or compost them. Wash hands after handling soil. Again, don’t eat the sprouts or beans.

Make it easier / make it harder

Easier (ages 4–5): Use one class cup that the adult manages, and have children take turns checking. Measure with a strip of paper or count paper clips. Record with drawings only.

Harder (ages 7–10):

• Experiment: set up two cups that differ in one way, such as light vs. dark cupboard, or warm vs. cool spot. Predict, then compare.
• Turn test: once roots are 2–3 cm long, lay one cup on its side for two days. Do roots curve back down?
• Graph it: plot root length by day on graph paper.

Inclusive and accessible options

• Use large beans such as lima or pinto for children with fine-motor challenges.
• For children who can’t handle wet materials, let them be the “measurer” or “recorder.”
• Read the steps aloud or post them with simple pictures; families can share the word for “bean” or “seed” in their home language.

Talk about it

• What came out first, the root or the shoot? Why might the plant need its root first?
• Where did the bean’s energy come from before it had leaves?
• What other seeds do people eat? (Peas, lentils, chickpeas, sunflower seeds. Grains like rice, oats and corn are seeds too, though botanists call each kernel a tiny fruit with the seed fused inside.)
• Why do farmers plant seeds in soil instead of paper towels?

Pair this with Where Foods Grow to connect seeds to roots, stems, leaves, flowers and fruits we eat.