Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 294 · 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? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
2. 2.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) plugging in the iron (d) cutting the lemon
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) white paper (c) lemon juice (d) a cotton bud
5. 5.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) yeast (d) a mirror
6. 6.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
9. 9.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
11. 11.⚖️ 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 ironing time (c) the kind of juice
12. 12.🛟 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
13. 13.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ 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
16. 16.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
17. 17.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
18. 18.🍋 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
19. 19.⚖️ 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 ironing time (c) how dark the writing is (d) the iron setting
20. 20.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
21. 21.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
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.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a battery cell (d) a balloon
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
25. 25.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) turmeric powder (d) a small bowl
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ 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) the same cotton bud (c) how dark the writing is
29. 29.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) reading the message
30. 30.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
33. 33.⚖️ 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
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a battery cell
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a magnet
37. 37.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
38. 38.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
40. 40.True or false: ironing the paper is a job for an adult. (a) False (b) True

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