The image of super sleuths tracking down the truth is a great one for learning. Magnifying Glass Cut-Outs are perfect for holding student photos
If you prefer DIY, magnifying glasses are easily made with simple shapes. 
- Cut the whole shape twice from black or brown paper, and then cut the magnifying glass circle alone from white paper.
- Have students write about themselves on the white circle and glue to one of the dark shapes. You can put those on the bulletin board, or on individual cards to hang on students’ desks.
- Glue student pictures to the second dark magnifying glass shape and attach with a transparent tape hinge so students can lift the magnifying glass to learn more about the student whose picture is shown on the front.
Make a totally easy reading corner bulletin board by pinning up dust jackets from mystery novels.
Some slogans for your detective theme bulletin board:
- Seeking out learning!
- Hot on the trail of math skills
- History Mysteries
- In hot pursuit of better writing
- Clued in to science
- Mrs. Smith’s Super Sleuths!
- Caught being good!
Cut footprints from paper and tape them to the floor — maybe even to the walls! — in a mysterious path. There are ready made footprints for the purpose, too.
Use washable ink stamp pads and put fingerprints all over the room. Students can decorate their own desk plates and notebooks in the same way. Introduce them to Ed Emberley’s Complete Funprint Drawing Book for fingerprint and thumbprint art ideas.
Once you have the theme established in your classroom, try out a few appropriate activities:
- Magnifying glasses are obviously great for science exploration. Get a class set of plastic magnifying glasses and have students use them to observe a small section of the classroom minutely for a great descriptive writing exercise. I like this assignment for helping students grasp the importance of narrowing a topic. Have each student write about one square foot of the classroom, one square of linoleum, or another small space. Then read their compositions aloud and see if the other students can identify the location being described.
- Create files for “suspects,” using the methods described for making science trading cards. Glue the cards to the inside of plain manila folders. The suspects can of course be anything on your curriculum list, from people “suspected of being important in our state’s history” to punctuation marks “suspected of helping make sentences clear.”
- Have a Morning Mystery each week. Again, choose subjects that fit your teaching plans. For example, you might have a Mystery Number. On Monday, give a tough clue, like “This number is a multiple of 9, but not an even number.” Have students write down the answer on a slip of paper and hide it in their desks or put their guesses into a jar. Each day, add a clue, till by Friday everyone should have been able to guess. If you gather the slips in a jar, you can then sort out the correct guesses and determine the proportion of correct guesses over the course of the week.
You’re ready to sleuth out the truth!
