過年要貼窗花，小年獸跟著學剪紙。紙是方格紙，紅色的格子就是窗花。第 1 關拖動摺線、轉換方向（直的、橫的、兩種斜的），按「對摺」看兩邊疊不疊得起來，要找出窗花所有的摺線（有的窗花有 2 條、4 條）；第 2 關窗花只剪好了摺線一邊的一半，孩子用手指塗出另一半，畫錯時會用虛線連起對稱的兩格，說明它們到摺線一樣遠；第 3 關紙摺成四摺，只看得到一角，孩子要畫出打開以後的另外三角。
適合年級：五年級（約 10～11 歲）。對應 108 課綱（十二年國教）數學單元：五年級「線對稱」。各版本教科書的單元順序不同，完整對照請看國小數學課綱對照表。免費、無廣告、不用註冊，手機、平板、電腦打開就能玩，題目有注音，也會念出來。
陪玩小提醒：可以拿一張紙真的摺一摺、剪一剪，打開來對照遊戲。對稱的兩點到對稱軸一樣遠，連起來的線和對稱軸垂直；正方形有 4 條對稱軸，長方形只有 2 條。
Little Nian is learning New Year window paper cutting on squared paper, where the red squares are the paper cut. In level 1 children drag a fold line, turn it (up and down, across, or either diagonal) and press Fold to see whether the two halves match, finding every line of symmetry (some paper cuts have 2 or 4). In level 2 only half of the paper cut is done and children paint the other half; mistakes are shown with dashed lines joining mirrored squares, which are the same distance from the fold line. In level 3 the paper is folded in four and only one corner shows: children draw the other three corners as they would look unfolded.
Suits Grade 5 (about age 10–11) in Taiwan. Taiwan curriculum (12-year basic education) unit: Line symmetry (Grade 5). Free with no ads and no sign-up, in Traditional Chinese with zhuyin and in English, read aloud. See the Taiwan elementary maths curriculum map.