A tea-colored riffle, granite walls, and a canvas dory. Stroke port or starboard to sit under the largest integer before the cobble bar reaches the bow. Built for sixth-grade number sense with positives and negatives.
Read the Cobbles
Two or three river stones slide toward the dory. Each face shows an integer. Find the largest — negatives sit below zero.
Take a Stroke
Tap Port or Starboard, or use the arrow keys. Each stroke yanks the dory one lane. Line up under the largest integer.
Clear the Riffle
A hit lights the cobble and adds 100 points, plus 50 for each step of the streak. A miss ships water and costs a life.
Open the Gorge
Eight clear riffles win the run. Three shipped rocks end it. Chase a new best on each difficulty.
Stroke the Dory
A foam bar of numbered cobbles slides down the riffle. Stroke port or starboard. The hull yanks one lane. Be under the largest integer when the bar hits the bow.
Largest Integer Wins
The open channel is always the greatest number. −8 loses to 7. −48 loses to 50. A miss ships a rock and breaks the streak.
The River Keeps Coming
The bar grows closer. You have to read the set and take a stroke before it arrives. Hits surge the hull and throw points off the cobble.
Three Currents
Easy uses two cobbles and small integers. Medium opens a third lane from −40 to 40. Hard clusters values from −99 to 99.
Riffle Run is a sixth-grade integer game. An autumn gorge holds a canvas dory and a sliding bar of numbered cobbles. The player strokes through the largest integer in each set. That is comparing positives and negatives, shown as a channel instead of a worksheet.
Negatives Have Weight
A cobble that reads −55 sits next to 50. Students feel that the larger integer is not the one with the bigger digits.
A Stroke, Not a Tap
The hull has to be under the right stone when the bar arrives. Reading the set is only half the play.
Instant Wake
A clear channel surges. A wrong mark ships water. Score and streak sit on the birch rail the whole run.
Keys and Touch
Arrows or A and D stroke the oars. On a phone, Port and Starboard are large. Mute sits on the left, away from fullscreen.
The largest integer. If the stones show −48, 50, and −55, the open channel is 50. −48 is greater than −55, but both lose to 50.
Yes, when every cobble is negative. Among −9, −2, and −7, the largest is −2.
Each stroke shifts one lane. Use Port / Starboard, or the left and right arrow keys. The hull yanks; it does not slide under a mouse.
How many cobbles appear, how large the integers get, and how fast the bar slides. Hard clusters close values so the comparison is tighter.
Sixth and seventh grade (about ages 11–13), when students order positive and negative integers. Stay on Easy to meet small negatives first.