Classroom activity Grade 6 Math

Earth's Water in 100 Counters: A Grade 6 Percent Model

A grade 6 hands-on activity where groups model Earth's water with 100 counters, placing 97 in ocean, 2 in ice, and 1 in fresh water, then compute with percent.

Grade: Grade 6
Subject: Math
Material: Classroom activity
Time: 30 min
Prep: Low prep
Materials: 100 counters or beads per group, 3 cups per group labeled Ocean, Ice, and Fresh, Printed recording handout

Standards

6.RP.A.3 Common Core Math

Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations, including finding a percent of a quantity and converting measurement units.

How this material aligns: Each counter stands for 1 percent of Earth's water, so placing 97, 2, and 1 counters and then rescaling to 200 in handout item 4 is the percent-of-a-quantity work this standard names.

All materials for 6.RP.A.3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will model the percent split of Earth's water using 100 counters.
Students will rescale a percent model from 100 counters to 200 counters.

Vocabulary

Fresh water: Fresh water is water with very little salt in it, the kind found in most rivers, lakes, and groundwater, and the kind people and land animals need to drink. It is different from the salty water that fills the oceans.

Also: percent, ocean, model

Teacher overview

This is a small-group activity for groups of three or four students. Each group builds a model of all the water on Earth using 100 counters, where one counter stands for 1 percent of the water. Groups place the counters into three labeled cups for ocean water, ice, and liquid fresh water, only part of which people can reach, which are the main places the water cycle stores water. The activity teaches the concept directly: by moving physical counters into cups, students see that almost all of Earth's water is ocean and that usable fresh water is a tiny share.

Activity Directions

Step 1 - Setup (5 min): Before class, place three cups labeled Ocean, Ice, and Fresh at each group's table, along with a pile of 100 counters and one recording handout. Arrange students in groups of three or four.

Step 2 - Frame the model (5 min): Tell students that the 100 counters together stand for all the water on Earth, and that each single counter stands for 1 percent of that water. Ask them to predict how many counters they think belong in the Ocean cup before they place any.

Step 3 - Place the counters (8 min): Have each group place 97 counters in the Ocean cup, 2 counters in the Ice cup, and 1 counter in the Fresh cup. Walk the room and ask groups to check that their three cups hold 100 counters in all.

Step 4 - Record and compute (8 min): Groups complete the recording handout, using their cups to answer the numbered questions. Remind them that the counter counts and the percents are the same numbers here, because there are 100 counters.

Step 5 - Debrief (4 min): Bring the class together and ask: if all 100 counters are Earth's water, why does the single Fresh counter matter so much? Then ask what the model would look like with 200 counters instead of 100, tying the activity back to scaling a percent.

Earth's Water in 100 Counters: A Grade 6 Percent Model — Grade 6 Math

Name: ____________________________ Date: ______________

Student Handout

Your group has 100 counters. All 100 counters together stand for all of Earth's water. Each counter stands for 1 percent.

Earth's water is about 97 percent ocean. Out of 100 counters, how many go in the Ocean cup?
About 2 percent of Earth's water is frozen in ice. How many counters go in the Ice cup?
The rest is liquid fresh water, and people can reach only part of it. How many counters go in the Fresh cup?
Suppose your group used 200 counters instead of 100. How many counters would go in the Ocean cup?
Explain why the fresh water people can use is only a small part of all Earth's water.

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: 97 counters.
97 percent of 100 counters is 97 counters in the Ocean cup.
Answer: 2 counters.
2 percent of 100 counters is 2 counters in the Ice cup.
Answer: 1 counter.
97 + 2 = 99 counters are placed, so 100 - 99 = 1 counter is left for the Fresh cup, matching about 1 percent.
Answer: 194 counters.
With 200 counters, each percent is 2 counters, so 97 percent is 97 × 2 = 194 counters in the Ocean cup.
Answer: It is less than 1 percent.
Almost all of Earth's water is salty ocean water or frozen ice, so the fresh water people can use is less than 1 out of every 100 parts.

Differentiation

Support

Give students who need it a cup already holding 97 counters so they can focus on the ice and fresh amounts and on the handout math. Pair each student with a partner who can help count by tens.

Extension

Ask students to imagine using 1,000 counters for the model. Have them find how many counters would go in each cup and explain how they scaled the three percents from 100 up to 1,000.

ELL supports

Label each cup with both a word and a small picture (waves for Ocean, an ice cube for Ice, a drinking glass for Fresh). Provide the sentence frame for item 5: "Usable fresh water is small because ___."

Extensions

Have groups pour the single Fresh counter's worth of a full water bottle into a small cup to see, by volume, how little liquid fresh water there is compared to all the water they started with.