Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 23 · 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.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) letting the paper dry
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a small bowl (d) an adult with an iron
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) an adult with an iron
6. 6.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
7. 7.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
9. 9.True or false: writing the message is a job for an adult. (a) False (b) True
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a battery cell (d) turmeric powder
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) the same cotton bud (d) how dark the writing is
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the kind of juice (d) the same cotton bud
16. 16.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
17. 17.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) a cotton bud
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a balloon (d) white paper
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a cotton bud (d) a magnet
21. 21.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
24. 24.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
25. 25.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) lemon juice
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) yeast (d) lemon juice
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
30. 30.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) white paper
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
33. 33.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
34. 34.True or false: cutting the lemon is a job for an adult. (a) False (b) True
35. 35.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
36. 36.⚖️ 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
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
40. 40.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True

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