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Classroom activity Grade 2 Science

Colored Water Up the Celery Stalks at Wistmoor School

A two-day grade 2 station rotation in which groups set celery and a white flower in dyed water, bag a leafy stem, and find where the water travels.

Objectives

  1. Students will trace dyed water from a cup into the parts of a plant.
  2. Students will collect and describe the water a bagged leafy stem gives off.
  3. Students will explain why a garden bed needs watering again after a few days.

Vocabulary

Key words: stalk, tube, petal, soak up, give off, wilt

Teacher overview

This is a two-day station rotation for three groups of six to eight students, set at the fictional Wistmoor School, where the class has been asked why the garden beds need watering again only a few days after a soaking. On day 1 each group sets up one celery stalk in red water, one white carnation in blue water, and one clear bag tied over a leafy celery top, then draws a prediction. On day 2 the same groups return to the three stations and find dye in the celery tubes, dye in the carnation petals, and a scatter of clear drops inside the bag, which together show that a plant pulls water up through itself and gives some of it back to the air. Many second graders picture a plant's water as sitting in the soil around it until the plant is thirsty, so the dye matters: it makes the water's route through the plant something students can point at.

Activity Directions

Setup before day 1 (moderate prep, about 10 minutes): Set out three stations, each with its own tray. Station 1 holds three cups of water with ten drops of red coloring stirred in and three celery stalks with the leaves on. Station 2 holds three cups of water with ten drops of blue coloring stirred in and three white carnations. Station 3 holds three clear sandwich bags, three twist ties, and three celery stalks with full leafy tops already standing in cups of water with ten drops of red coloring stirred in. Cut the bottom off every celery stalk and every carnation stem yourself, at the station, just before each group arrives, and keep the knife with you the whole time. Tell students plainly that nothing at these stations is food today and that nobody tastes or drinks anything.

Day 1, station rotation (15 min, 5 min per station): Groups rotate through all three stations in order.

  1. At Station 1, each group stands one freshly cut celery stalk in a cup of red water and writes the group name on the cup with tape.
  2. At Station 2, each group stands one freshly cut carnation in a cup of blue water and labels that cup the same way.
  3. At Station 3, each group slides a clear bag over the leafy top of one of the celery stalks already standing in red water, then closes the bag around the stalk with a twist tie so that only the leaves are inside.

Day 1, prediction and share (5 min): Back at their seats, students draw the celery and the carnation as they look now on the handout and draw what they think each will look like tomorrow. Ask one student from each group to say a prediction aloud, and write the three predictions on chart paper.

Day 2, station rotation (18 min, 6 min per station): Groups return to the same three stations, in the same order, and record what they find.

  1. At Station 1, students look at their celery stalk from the side and count how far up the red has traveled. When the group is ready, cut a slice across the stalk yourself so that students can see the ring of red dots, and tell them each dot is the end of a tube that carries water up the stalk.
  2. At Station 2, students look at the edges of the carnation petals and draw exactly what they see.
  3. At Station 3, students look at the inside of the bag without opening it, and describe what has collected there.

Day 2, debrief (7 min): Bring the class together with all three stations visible. Ask: "The red water started in a cup. Name every place we found it today." Then ask: "The drops in the bag are clear, not red. Where did that water come from, and where was it going?" Close by returning to the garden beds and asking why a bed that was soaked on Monday can be dry again by Thursday. The rotation ends when every group has visited all three stations on day 2 and completed the handout.

Colored Water Up the Celery Stalks at Wistmoor School — Grade 2 Science
Name: ____________________________ Date: ______________

Student Handout

Day 1. Draw your celery stalk and your carnation as they look today. Then draw what you think each one will look like tomorrow.

Day 2. Answer these questions.

  1. Where did the red water start out?
  2. Name one part of the celery stalk where you found the red color on day 2.
  3. Your teacher cut across the stalk. Tell what the red dots are.
  4. What color were the edges of the carnation petals on day 2?
  5. Drops collected inside the bag. Those drops were clear, not red. Tell where that water came from.
  6. The garden bed was soaked on Monday and dry again on Thursday. Use what you saw today to tell why.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: In the cup at Station 1. The red coloring was stirred into the water before the celery was stood in it.
  2. Answer: Accept any part where the class actually finds color, most often the strings running up the stalk, the cut top, or the small leaves at the top.
  3. Answer: Accept any answer saying the dots are the ends of the tubes that carry water up the stalk. Answers naming them straws or pipes are fine at this grade.
  4. Answer: Blue, or blue along the edges and veins. Accept the answer that matches the class flowers, since some petals color faster than others.
  5. Answer: Accept any answer saying the water came out of the leaves, or came up through the stalk from the cup and left through the leaves. The clear color is the clue that the plant kept the dye and passed on the water.
  6. Answer: Accept any answer using the day's evidence, such as the plants pulling water up out of the soil and giving some of it back to the air, so the bed dries out and needs watering again.

Differentiation

Support

Assign these students the job of the marker at each station, labeling cups and drawing rather than writing, and give them a handout with the celery and carnation outlines already printed so they only color what they see. Let questions 2 and 4 be answered by coloring a box instead of writing a word.

Extension

Split the bottom of one celery stalk lengthwise yourself for a group, and have the group stand one half in red water and the other half in blue water, then predict what the top of the stalk will look like on day 2 and write why.

ELL supports

Keep one finished stalk from a previous class at the front all week so students can see the end result while they learn the words. Provide the labels stalk, leaf, petal, cup, tube, and drops on cards that students place on the real objects, and allow question 5 to be answered by pointing at the leaves.

Extensions

Set one carnation in plain water and one in no water at all, in the same light, and check both after two days. Ask students which one wilted and how that result fits what the bagged leaves showed about water leaving a plant.