Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 971 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a cotton bud (d) white paper
2. 2.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
4. 4.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: white paper is needed for the secret lemon message. (a) True (b) False
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
8. 8.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
12. 12.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) a battery cell (d) a mirror
14. 14.True or false: reading the message is a job for an adult. (a) True (b) False
15. 15.True or false: plugging in the iron is a job a child can do. (a) True (b) False
16. 16.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a battery cell (d) turmeric powder
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.⚖️ 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) how dark the writing is (c) the iron setting (d) the ironing time
22. 22.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a cotton bud (d) yeast
24. 24.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a cotton bud (d) yeast
29. 29.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) white paper (d) a small bowl
31. 31.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) plugging in the iron (d) letting the paper dry
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.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
34. 34.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) reading the message
35. 35.⚖️ 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 measure it (c) we change it
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) turmeric powder (d) a cotton bud
37. 37.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False

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