Mystery Number Slides
A vibrant 7-slide presentation for the Mystery Number Detectives lesson. It includes a warm-up, the Khan Academy video embed, a pause point for prediction, activity instructions, and a reflection prompt.
Prediction Slips Worksheet
A printable sheet of four Prediction Slips for the video pause point. Students complete equations for 16-19 to identify the 10 + __ pattern.
Mystery Bag Log Worksheet
A student recording sheet for the "Mystery Bags" activity. Students record the bag's number, the ten-stick, and calculate how many ones were added.
Mystery Number Teacher Guide
A comprehensive teacher case file (guide) for the Mystery Number Detectives lesson. Includes lesson flow, critical video pause points, gear checklist, and common misconceptions.
Mystery Bag Labels Resource
Printable labels for the Mystery Bag activity. Includes labels for numbers 11-19 with a detective theme to be taped onto brown paper bags.
Detective Journal Page
A reflective journal page for the end of the lesson. Students explain why the number 11 is special and draw its place value representation (one ten and one one).
Mystery Number Answer Key
A teacher answer key and quick-reference guide for the Mystery Number Detectives lesson. Includes solutions for prediction slips, mystery bag missing addends, and reflection prompts.