Perceptle Split practice.
A simple line. A fraction of its length. Learn to see the relationship before you make your mark.
Ready when you are.
Drag the marker to the requested part of the line, measured from the named end. Release to submit.
Independent practice round · Randomized each time · Best score saved locally
First choose the right starting point.
- Press Start to receive a fraction or percentage and a named starting end: left or right.
- Drag the marker to the requested distance from that end. For one quarter from the right, the marker belongs three quarters across from the left.
- Release to submit. The result shows the target, your mark, and the difference as percentage points of the whole line.
A useful way to improve
Find the halfway point first. Divide one half again for quarters, or imagine equal thirds or fifths. Check which end is named before you move: one third from the right is the same location as two thirds from the left.
What the score means
Error is the absolute difference between your mark and the correct position, divided by the full line length. The normal tolerance is 0.05, or five percentage points of the line. The target and pointer use normalized positions, which stay the same when the screen resizes.
Every score is out of 100. A fresh target appears each round, and your best for this exercise stays in your browser. Read the score curve and grade thresholds for worked examples.
Touch and keyboard controls
Drag the marker on the line and release to submit. The keyboard slider is always measured from the left; its output shows that position. Use Lock split to submit a slider answer. Normal page scrolling works outside the exercise field.
If you switch apps or hide the page during an active round, it stops without recording a score. Resize the window freely: targets are drawn in the same logical field and saved results remain intact.
Teaching examples · not today’s puzzle or an official answer
Split example: three eighths from the right is five eighths from the left.
Read the named endpoint before estimating. A target of 3/8 from the right uses the right edge as its starting point, so its position measured from the left is 1 − 3/8 = 5/8 = 62.5%.
Separate a direction error from a small miss
Marking 37.5% from the left for this target uses the wrong endpoint. It misses by 25 percentage points of the whole line. Repeating that mark more accurately will not fix the direction error.
A mark at 57.5% from the left is a different case: the endpoint is understood, but the mark is 5 percentage points short of the correct 62.5%. With a normal tolerance of 0.05, it scores 61 / 100.
Change one thing next round
Say the named end first. Use halves, quarters, or thirds as anchors, then place the remaining fraction. Read the result’s “correct position from the left” alongside your mark: a mirrored location suggests an endpoint mix-up; a nearby mark suggests proportion estimation. Change the relevant step rather than moving every future answer in the same direction.
Try Split and name the starting end ↑Diagnose repeated Split errors →See Friday fractions longer than the line →Another way to trust your instincts.
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