Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 706 · 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.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) ironing the paper
2. 2.⚖️ 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
3. 3.⚖️ 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 kind of juice (c) the iron setting (d) the same paper
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) plugging in the iron
6. 6.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
8. 8.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
9. 9.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) a cotton bud
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) physical (d) magnetic
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) lemon juice
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
14. 14.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
15. 15.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
16. 16.True or false: reading the message is a job for an adult. (a) False (b) True
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) turmeric powder
18. 18.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) reading the message
19. 19.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
20. 20.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
21. 21.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) plugging in the iron
22. 22.True or false: putting the iron away is a job for an adult. (a) True (b) False
23. 23.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) an adult with an iron (d) a cotton bud
26. 26.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
28. 28.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a cotton bud (d) lemon juice
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
31. 31.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
35. 35.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) reading the message (d) letting the paper dry
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
38. 38.True or false: reading the message is a job a child can do. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
40. 40.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True

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