Water for Schools
Menu

Classroom activity Kindergarten Science

The Soak Test at Clovergate School: Grass Against Pavement

A kindergarten activity where the class pours the same cup of water on a tilted grass tray and a tilted pavement tray, then compares what runs off each one.

Objectives

  1. Students will compare how much water runs off a grass tray and a pavement tray.
  2. Students will explain that hard ground sends rain running while soft ground takes it in.
  3. Students will name one change that would keep more rain out of the schoolyard drain.

Vocabulary

Key words: soak, run off, hard, soft, tilt, compare

Teacher overview

Clovergate School is a fictional school with the same two kinds of ground your own yard has: a hard blacktop and a soft grass field. This activity puts those two surfaces side by side on a table as tilted trays, pours the same amount of water on each, and catches whatever runs off the low edge in identical clear cups. The comparison is what the whole activity rests on, so the two trays must be tilted the same amount and receive the same water, poured the same way. Run it as a whole-class demonstration on a table students can circle, with two students pouring and two more holding the catch cups.

The idea worth testing here is the common belief that rain soaks into any ground, pavement included, and that a puddle on the blacktop is simply water waiting its turn to sink in. The catch cups make the difference visible in one look: the pavement tray sends nearly all of its water into the cup while the grass tray holds most of its water back. Expect students to predict that both cups will fill the same, and record those predictions before the pour so the class has something to check its result against.

Activity Directions

  1. Set up the two trays (6 min). Prop one end of each tray on the same small stack of books so both tilt by the same amount. Fill the first tray with soil and press a square of sod or a thick damp sponge onto it, and lay the flat plastic lid or tile across the second tray so its surface is smooth and hard. Set an identical clear cup under the low edge of each tray. Tell the class that the first tray is the grass field and the second tray is the blacktop.
  2. Take predictions (4 min). Ask which cup will catch more water, and have every student point at one tray. Count the pointing hands for each and write the two counts on the chart paper. Ask two students to say why they pointed as they did, and write their reasons underneath.
  3. Pour on the grass tray (6 min). Have a student pour one measuring cup of water slowly along the high edge of the grass tray while the class watches where the water goes. Ask what the class sees happening on the tray itself, and let them say that the water is sinking in or disappearing into the sod. Leave the catch cup in place and do not empty it.
  4. Pour on the pavement tray (6 min). Have a second student pour the same amount of water, at the same slow speed, along the high edge of the pavement tray. Ask the class to watch the low edge and say what is different. Expect students to call out that the water is running straight off.
  5. Compare the two cups (6 min). Lift both catch cups and hold them side by side at student eye height. Ask which cup holds more water and how they can tell, then set the cups down and read the prediction counts back off the chart. Give the class the sentence to say together: "The hard ground sent more water away."
  6. Debrief and connect it to the schoolyard (7 min). Ask three questions in order: Where did the grass tray's water go if it never reached the cup? Which tray is more like our blacktop? On a rainy day, which part of our yard sends the most water down the drain? Then ask each student to name one change that would keep more rain out of the drain, such as leaving the grass field alone, planting a strip beside the pavement, or putting a garden bed at the low corner. Write three of those answers on the chart and have students draw the one they picked.

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

Differentiation

Support

Let these students hold the catch cups during both pours so they feel the weight change and see the water arrive. Ask the comparison question with the two cups held directly against each other rather than by describing the two water lines from a distance.

Extension

Ask these students to run a third tray with bare soil and no sod and to say where its result falls compared with the other two. Have them predict what would happen if the pavement tray were tilted more steeply, then test it and report to the class.

ELL supports

Pre-teach soak, run off, hard, and soft by pressing a student's hand first onto a wet sponge and then onto a plastic lid while each word is said. Accept pointing at a tray or a cup as a full answer through every step, and provide the sentence frame "The water went ___" with the words in and away on cards.

Extensions

Walk the class outside during or just after a rain and find one spot where water is standing on pavement and one spot where the grass has taken it in, then have students name each one using the words from the trays. Leave both trays on the windowsill through the afternoon and check them at the end of the day so the class can see that the grass tray is still damp while the pavement tray has dried.