Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 931 · 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.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) white paper (d) yeast
3. 3.True or false: ironing the paper is a job a child can do. (a) False (b) True
4. 4.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) yeast
7. 7.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
11. 11.⚖️ 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 kind of juice (c) the same cotton bud (d) the ironing time
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a mirror (d) a cotton bud
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) turmeric powder (d) an adult with an iron
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
17. 17.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a mirror (d) a magnet
18. 18.True or false: reading the message is a job a child can do. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
20. 20.True or false: cutting the lemon is a job for an adult. (a) False (b) True
21. 21.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) plugging in the iron
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a cotton bud (d) lemon juice
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) turmeric powder (d) a magnet
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) False (b) True
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
26. 26.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
27. 27.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
28. 28.⚖️ 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
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
31. 31.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) writing the message (d) cutting the lemon
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
35. 35.🛟 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
36. 36.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) a battery cell (d) a mirror
39. 39.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
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