Classroom activity Grade 1 Math

Swanmere Marsh's Number Line Walk: A Grade 1 Rain and Sun Game

A 30-minute grade 1 activity where students walk a floor number line to model rain filling and sun drying a marsh pool, solving word problems within 20.

Grade: Grade 1
Subject: Math
Material: Classroom activity
Time: 30 min
Prep: Low prep
Materials: Masking tape and index cards to build a floor number line from 0 to 20, One paper raindrop marker per group, Blue and yellow cards labeled rain and sun, Printed student handout, One clipboard per group

Standards

1.OA.A.1 Common Core Math

Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

How this material aligns: Students act out add-to, take-from, and compare problems within 20 by walking a floor number line, which is one of the representations 1.OA.A.1 allows. Problems 3 and 4 place the unknown in the change position, and problems 5 and 6 are compare situations.

All materials for 1.OA.A.1 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-09-03.

Objectives

Students will act out add-to and take-from problems within 20 by walking a number line.
Students will find a missing change amount by counting the steps they walked.
Students will compare two pool amounts and tell how many more.

Vocabulary

Key words: number line, rain, dry up, how many more, marsh

Teacher overview

Swanmere Marsh is a made-up wetland with a shallow pool that swells after a storm and shrinks again during a dry stretch, which is the water cycle at a scale a first grader can watch across a single week. This activity builds a number line from 0 to 20 on the classroom floor and asks a student to stand on the number of cups in the pool, then step forward when a rain card is drawn and step backward when a sun card is drawn. A step forward is the add-to move, a step backward is the take-from move, and the number of steps walked is the change, so a student who forgets which way to face has to reread the story rather than guess. Four or five students per group keeps everyone stepping.

Activity Directions

Before class, tape a number line from 0 to 20 on the floor, at least six feet long, with one index card per number. Build a second line if the class is larger than fifteen students.
Group students in fours and give each group a paper raindrop marker and the handout on a clipboard.
Explain the two moves. Rain means step forward toward the bigger numbers, and sun means step backward toward the smaller numbers.
Model one round with a story that is not on the handout. The pool holds 4 cups, rain adds 3 cups, so the walker stands on 4, takes 3 steps forward, and lands on 7.
Groups work through the handout in order. One student walks, one student reads the problem aloud, one student counts the steps out loud, and one student writes the landing number. Roles rotate after every problem.
Watch for walkers who slide past their landing number without counting steps, and ask those groups to walk the round again while the counter taps each card.
End the game when every group finishes all six problems, or after eighteen minutes of walking, whichever comes first.
Debrief on the line itself. Ask which problems made the walker step forward and which made the walker step backward, and ask what would happen on the line if a whole week passed with no rain and no sun.

Swanmere Marsh's Number Line Walk: A Grade 1 Rain and Sun Game — Grade 1 Math

Name: ____________________________ Date: ______________

Student Handout

Stand on the start number. Rain means step forward. Sun means step backward.

The pool holds 6 cups. Rain adds 7 cups. Where does the walker land?
The pool holds 15 cups. Sun dries up 8 cups. Where does the walker land?
The pool holds 9 cups. Rain adds some cups. The walker lands on 16. How many cups did the rain add?
The pool holds 18 cups. Sun dries up some cups. The walker lands on 12. How many cups did the sun dry up?
Pool A holds 8 cups. Pool B holds 14 cups. How many more cups does Pool B hold?
Pool A holds 12 cups. Pool B holds 5 fewer cups than Pool A. How many cups does Pool B hold?

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

Answer Key

Answer: 13 cups. Start on 6 and take 7 steps forward, because 6 plus 7 is 13.
Answer: 7 cups. Start on 15 and take 8 steps backward, because 15 minus 8 is 7.
Answer: 7 cups. Walking from 9 up to 16 takes 7 steps, because 9 plus 7 is 16.
Answer: 6 cups. Walking from 18 down to 12 takes 6 steps, because 18 minus 6 is 12.
Answer: 6 cups. Walk from 8 up to 14 and count 6 steps, because 14 minus 8 is 6.
Answer: 7 cups. Start on 12 and take 5 steps backward, because 12 minus 5 is 7.

Differentiation

Support

Give these groups a number line from 0 to 10 taped beside the long one and problems 1, 2, and 5 only, rewritten with smaller numbers by the teacher on the spot. Stand with the walker and tap each card as it is counted.

Extension

Ask these groups to write a seventh round in which the pool starts at an unknown number, rain adds 4 cups, and the walker lands on 13, then to walk backward to find the starting number and explain the move.

ELL supports

Attach a small blue raindrop icon to the word rain and a small yellow sun icon to the word sun on every card, and use the same forward and backward arm motion each time the words are said. Let students answer by standing on the landing card before anyone writes a number.

Extensions

Set a shallow pan of water on a sunny windowsill, mark the level with tape each morning for a week, and walk the class number line to show how far the level moved between two marks.