Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 807 · 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 yeast for the secret lemon message? (a) not needed (b) needed
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a mirror (d) yeast
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
6. 6.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) letting the paper dry
7. 7.⚖️ 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
8. 8.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) writing the message
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a magnet
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) lemon juice (d) white paper
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 keep it the same (c) we change it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a battery cell (d) lemon juice
15. 15.True or false: reading the message is a job a child can do. (a) False (b) True
16. 16.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
17. 17.True or false: white paper is needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ 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
19. 19.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ 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
24. 24.True or false: reading the message is a job for an adult. (a) True (b) False
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a balloon (d) an adult with an iron
26. 26.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
28. 28.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
30. 30.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
32. 32.⚖️ 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
33. 33.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) cutting the lemon
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
35. 35.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ 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 keep it the same (c) we change it
39. 39.True or false: ironing the paper is a job a child can do. (a) True (b) False
40. 40.True or false: writing the message is a job for an adult. (a) True (b) False

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