Get the torn diary page out of the trash in the kitchen. Then get the piece of paper from the kitchen table, which is a secret message. Go back to C.J's room and jump onto the lamp to bend it close to the desk. Turn on the lamp, then click 'use' on the secret message in your inventory. You never actually put the diary under the light. only the paper.
Put it under the light!
You get the diary key and the torn page. Use the diary key on the diary and combine the torn page. Then jump on the lamp as low as it can go and turn it on. Put the paper under it.
The secret message (from the kitchen table).
Duck under all the objects that are bigger than you.
under a rock inside a cave
Along with the diary page (from the trash) and the diary key (from the aquarium), the note reveals what CJ has been doing. Take it to the computer desk and bend the lamp down close to the desk top and turn it on. Place the note under the hot bulb and the message will be revealed.
Under the bed in the girl's room
It tells you to look for her under the microscope.
The evidence is in the thumb drive under CJ's bed.
The diary drawings mean that CJ has successfully built a shrink ray, which is what was used on you. You need the missing diary page from the trash can in the kitchen, and the diary key from the aquarium tank in order to see the diary. The other things you need are the thumb drive from under her bed (use the fan) and the secret message from the kitchen table (knock over the oil on the shelf, fill the cat bowl, then slide it to the table). The heavy grape will let you use the toaster to reach the top of the refrigerator, as you will later need the toy truck control. The telescope coordinates are on the bulletin board (87, 16) and the morse code book is on the bed.
you put it under c.j`s lamp to get the message
Put it under the lamp because its an invisible ink message.