Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 440 · 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 of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
3. 3.⚖️ 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 keep it the same (c) we measure it
4. 4.True or false: ironing the paper is a job a child can do. (a) False (b) True
5. 5.⚖️ 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
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) lemon juice (d) a cotton bud
8. 8.⚖️ 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
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
11. 11.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) white paper (d) turmeric powder
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
14. 14.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
15. 15.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) ironing the paper
16. 16.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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) True (b) False
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a small bowl (d) an adult with an iron
19. 19.⚖️ 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
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the ironing time (d) the same paper
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a balloon (d) lemon juice
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the iron setting (d) the kind of juice
23. 23.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
25. 25.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) a cotton bud
27. 27.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) an adult with an iron
29. 29.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a magnet (d) white paper
31. 31.True or false: putting the iron away is a job for an adult. (a) True (b) False
32. 32.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a cotton bud (d) a magnet
33. 33.True or false: writing the message is a job a child can do. (a) False (b) True
34. 34.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) turmeric powder (d) a cotton bud
38. 38.True or false: putting the iron away is a job a child can do. (a) False (b) True
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
40. 40.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper

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