Sheets Bootcamp is a practice app for learning Google Sheets. Each lesson is a few short steps inside a real spreadsheet in your browser: you read the task, type the formula, and the app checks your answer right away. 70 lessons across 12 units take you from your first formula to IF, SUMIFS, lookups, text and dates, with 5 build-it-yourself projects and practice rounds that use new numbers every time. Unit 1 is free with a free account.
