Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 66 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) lemon juice (d) a small bowl
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
3. 3.True or false: writing the message is a job for an adult. (a) True (b) False
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) a cotton bud (d) lemon juice
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
7. 7.⚖️ 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
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a small bowl (d) a magnet
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
12. 12.⚖️ 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
13. 13.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
14. 14.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
17. 17.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
18. 18.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
19. 19.True or false: letting the paper dry is a job for an adult. (a) False (b) True
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
24. 24.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) an adult with an iron (d) yeast
28. 28.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
29. 29.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) letting the paper dry
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) letting the paper dry
32. 32.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
33. 33.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
34. 34.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.⚖️ 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 kind of juice (d) the same cotton bud
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False

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