Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 604 · 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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
2. 2.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
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) only an adult (b) any child (c) whoever is fastest (d) the youngest child
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
6. 6.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
8. 8.⚖️ 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 keep it the same (c) we measure it
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) an adult with an iron
10. 10.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
12. 12.⚖️ 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
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
14. 14.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) ironing the paper (d) dipping the cotton bud
15. 15.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) cutting the lemon (d) letting the paper dry
16. 16.True or false: turmeric powder 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? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the iron setting
18. 18.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) a balloon
22. 22.True or false: white paper is needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
28. 28.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
29. 29.True or false: cutting the lemon is a job a child can do. (a) False (b) True
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) lemon juice (d) white paper
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) a mirror
35. 35.⚖️ 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
36. 36.⚖️ 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
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) lemon juice
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) ironing the paper

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