MILESTONE TEACHERS
Fraction Repair Lab · Free unit-size lesson

Predict. Test. Explain. Check.

Make the model
prove it.

A fraction claim has gone wrong. Change the model, find the mistake, and make a repair you can explain.

One complete free lab10–15 minutesOne device or a projector

On the workbench

1 / 41 / 6Same-sized whole. More equal parts. What happens to each piece?

Start with the piece-size mix-up.

Teacher start: one short lesson, one useful conversation

Choose a route from the student's actual work. Predict first, let students test a model, then ask them to explain before revealing an example. Finish with two fresh questions and listen to the reasoning. A correct click alone does not demonstrate understanding.

Grades 4–6: unit size and equivalence use foundational fraction concepts. This free lab practises unit-fraction meaning. The full diagnostic covers ten fraction pathways.

All controls work with keyboard or touch; there is no dragging or timer. Read questions aloud, allow an oral explanation, or sketch the strip models on paper. Models have text descriptions. No name is needed. Work stays only in this open page; download notes before closing or refreshing. A connection is needed to load this page. Your answers stay in this tab; the activity does not send them to a server or save them automatically. No account is needed.

Watch the 42-second teacher walkthrough

See the lesson's teaching sequence before you begin. This silent animation has on-screen text and a full transcript below.

Read the complete walkthrough transcript

Predict (0–5 seconds). Is one sixth bigger than one fourth? Two equal-length wholes show one of four equal parts shaded and one of six equal parts shaded. Ask for a first thought before changing the model.

Test equal wholes (5–13 seconds). Keep both wholes the same size. One fourth is greater than one sixth: more equal parts make smaller pieces. Change the second bar to thirds. One third is greater than one fourth: fewer equal parts make larger pieces.

Change the whole (13–21 seconds). Strip B's whole is now twice as long as strip A's whole. One sixth of B is longer than one fourth of A. Compare actual lengths when the wholes differ; this does not change the numerical fact that one fourth is greater than one sixth.

Explain (21–28 seconds). Example reasoning: when the wholes are the same size, splitting them into more equal parts makes each piece smaller. Students can speak, sketch or type. Listen for the reason, not just the answer.

Fresh check (28–35 seconds). With same-sized wholes, which is greater: one third or one fifth? Pause and explain. One third is greater because thirds are larger than fifths of the same whole.

Try it (35–42 seconds). This complete free lesson supports a 10–15-minute conversation for Grades 4–6, using one device or a projector. No sign-in or purchase is needed.