Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 928 · 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) letting the paper dry (b) ironing the paper (c) putting the iron away (d) plugging in the iron
2. 2.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) yeast
4. 4.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
5. 5.⚖️ 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
6. 6.🍋 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
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same cotton bud (c) how dark the writing is (d) the iron setting
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) a cotton bud
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) putting the iron away (d) plugging in the iron
12. 12.⚖️ 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
13. 13.🧺 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) a magnet (d) a cotton bud
14. 14.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
16. 16.True or false: letting the paper dry is a job a child can do. (a) False (b) True
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) yeast (c) lemon juice (d) white paper
18. 18.🧺 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
19. 19.True or false: white paper is needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) white paper
21. 21.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
22. 22.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
23. 23.True or false: reading the message is a job for an adult. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) lemon juice
26. 26.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
29. 29.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
30. 30.⚖️ 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
31. 31.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) putting the iron away
34. 34.⚖️ 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 ironing time
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
36. 36.⚖️ 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 iron setting
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a battery cell

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