Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 813 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
3. 3.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
7. 7.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) lemon juice (d) an adult with an iron
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a small bowl (d) a cotton bud
10. 10.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
11. 11.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) cutting the lemon (d) putting the iron away
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) white paper (d) a balloon
13. 13.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
14. 14.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) ironing the paper
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a balloon (d) yeast
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) white paper (d) a balloon
17. 17.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the ironing time (c) how dark the writing is (d) the iron setting
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
20. 20.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) turmeric powder (d) a magnet
22. 22.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) plugging in the iron
23. 23.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) reading the message
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
25. 25.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) yeast (d) a cotton bud
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: reading the message is a job for an adult. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
30. 30.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) reading the message
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the iron setting (d) the kind of juice
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) an adult with an iron (d) a mirror
33. 33.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
34. 34.True or false: ironing the paper is a job a child can do. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
37. 37.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a cotton bud (d) a battery cell
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
40. 40.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids