Spanish numbers sudoku

This sudoku puzzle uses the first nine Spanish numbers in their written form. The students need to write each number out as a word, in an empty cell. However, each row, column, and 3x3 box must contain only one use of each number.

This is a great way to learn numbers with an element of challenge. To make it more competitive, add a time limit, with a prize for the first to finish. It's a perfect transition activity for a first lesson with a new year 7 group, as all the Spanish numbers are provided on the sheet.