Shelly's Tide-Line — Measurement Line Plots (Grade 2)

About this activity

Shelly the hermit crab measures shells and shows their lengths on a tide-line — a line plot scaled from 1 to 8 — and the child reads the X's stacked over each number to answer how many are 5 long, which length is most common, or how much longer the longest is than the shortest, and in other rounds places a new X. It's a free, interactive Grade 2 math activity that runs in the browser, with no account.

The big idea is reading and building a measurement line plot, the focus of 2.MD.D.9. The questions push past simple counting: comparing two columns, finding the mode, and taking the difference between the longest and shortest all ask the child to interpret the picture of the data, not just tally one stack. Because some rounds have the child place an X, they also learn that each measurement becomes one mark at its length.

It is aligned to Common Core 2.MD.D.9 — generating measurement data and showing it on a line plot marked in whole-number units. No timer, no score — just calm, playful practice.

What's inside this activity

• Designed for Grade 2 learners (ages about 7–8)
• Common Core strand: Measurement & Data
• Aligned to Common Core standard 2.MD.D.9

How to play

Read the X's stacked over each number on Shelly's tide-line.

Answer the question — how many, how many longer, the most common, or the difference — or place the new X, then press Check.

Not quite? Try again as many times as you like — there is no timer and no score.

What your child practices

• Counting the X's above a number to find how many shells are that length
• Comparing two lengths to see how many more are at one than another
• Finding the most common length (the mode) on the plot
• Placing a new measurement as an X above the right number

Learning goals

Read and build a measurement line plot in whole-number units — the focus of Common Core 2.MD.D.9

Compare lengths and find the most common length from the data

Connect each measurement to a single mark on the plot