Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 586 · 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? True or false: the ironing time is kept the same. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) reading the message
3. 3.⚖️ 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 same cotton bud (c) the same paper (d) how dark the writing is
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
5. 5.True or false: reading the message is a job a child can do. (a) True (b) False
6. 6.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) lemon juice (d) a balloon
8. 8.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ 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) how dark the writing is (c) the iron setting
11. 11.🍋 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
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) a small bowl
13. 13.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
14. 14.True or false: plugging in the iron is a job for an adult. (a) False (b) True
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
16. 16.True or false: white paper is needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ 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
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) letting the paper dry
21. 21.⚖️ 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
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
23. 23.⚖️ 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 measure it (c) we keep it the same
24. 24.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
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 measure it (b) we change it (c) we keep it the same
27. 27.🍋 Secret message: who does this step — putting the iron away? (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? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
32. 32.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
34. 34.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
36. 36.True or false: putting the iron away is a job a child can do. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
38. 38.⚖️ 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 kind of juice (c) the same cotton bud
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) yeast (d) a cotton bud
40. 40.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it

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